Role of anti-HLA
Preformed DSA are detected before Tx and de novo DSA are detected post Tx due to sensitization in conditions like pregnancy, blood transfusion or previous Tx. Risk factors of de novo DSA formation:
HLA mismatch (especially class II);the most important.
.Young age ,deceased donor kidney
.Preformed DSA
.Subtherapeutic IS dose due to infection, malignancy or conversion to less potent IS.
.Inflammation due to surgery, infection or TCMR.
DSA with its different types injure endothelium and can lead to acute ABMR, chronic ABMR ,subclinical rejection and reduction pf patient and graft survival. De novo DSA have poorer outcome than preformed DSA.
Monitoring of DSA is either diagnostic eg in case of subclinical & clinical ABMR ,therapeutic to tailor IS protocols ,or for prognostication.
Method
usually using SBA for its sensitivity and specificity.
C1q is used for detecting complement fixing DSA.
DSA assay usually done once in the first 3 months following transplantation and later if indicated eg desensitized patients ,non adherence ,need for IS escalation ,graft dysfunction or transfer to another center. Some protocol implement DSA regular annually or 3 monthly for first 3 years. monitoring
Renal biopsy is indicated once DSA are detected
Treatment is started with detected DSA and BPABMR or in case of rapidly increasing DSA in desensitized patients with normal or near biopsy findings.
Alyaa Ali
3 years ago
Donor specific antibodies are two types
preformed circulating anti HLA antibodies which were the result of a sensitization event pretransplant as blood transfusion ,pregnancy or previous transplantation
Denovo DSA : they are clinically relevant antibodies directed against donor specific HLA class I and class II mismatch detected post transplant which typically developed within the first 2 years of the transplantation due to insufficient immunosuppression or poor compliance with immunosuppressive therapy.
when not treated clinically , it results in immune attack of the transplant organ ,it attacks the endothelial of graft resulting in subsequent antibody mediated rejection and graft loss
Antibody mediated rejection can be acute due to preformed antibodies or Denovo DSA that develop in the early post transplant period and can be late chronic process due to development of Denovo DSA antibodies later
sub clinical antibody mediated rejection where preformed HLA antibodies and Denovo DSA take months to years to produce chronic vascular changes and graft loss
presence of HLA antibodies kidney graft loss
Denovo DSA is an independent predictor of poor patient survival Monitoring of DSA post transplant
Luminex based single antigen beads allow for highlysensitivedetermination of a patient antibody profile and discrimination between donor specific and non specific antibodies serial monitoring of DSA is more valuable than single point testing especially in post transplant period , choosing monitoring frequency based on patient individual risk of developing AMR
early detection and treatment improve the outcomes
AMAL Anan
3 years ago
The primary cause of poor graft survival is late stage graft failure secondary to AMR.
Performed circulating antibodies in recipients result in pre-transplant sensitisation.
Post-transplant development of clinically antibodies directed against donor specific HLA class I and class II mismatches which increase risk of graft loss or rejection.
DSA attacks endothelium of graft results in AMR and progression of development of DSA leads to chronic changes which reflected on graft function and survival.
Up to 96% of rejected allografts develop some level of detectable DSA .
There is association between anti-HLA antibodies and development of chronic renal failure which leads to renal allograft failure.
Early detection and removal of DSA pre-and post- transplant may prevent allograft loss.
Solid-phase assay helps in detection of DSA pre-and post-transplant.
AMR presents early and late after transplantation.
Sub-clinical antibody mediated rejection due to DSA which develops without immediate impairment of graft function.
High graft failure rates associated with denovo DSA post liver transplant recipients 62% and in post-kidney transplant recipients reaches 24%.
Patients with performed DSA and those who develop de novo DSA increase risk of having chronic rejection.
High frequency of denovo DSA or patients with non-adherence to immunosuppressive therapy. represented by micro circulation inflammation in late kidney biopsy.
SAMR are found in patients with performed DSA ,some of them C4d stain negative for SAMR.
In cardiac transplant , 15 years graft survival at 52% in those who de novo antibodies during first year post transplant while 15 year graft survival at 40% in those de novo DSA developed after one year post transplant, the latter associated with poor outcomes and grade 3 , worse ACR.
De novo antibodies productions cause subclinical AMR which associated with long term graft dysfunction with negative outcomes which developed later .
Development of de novo DSA in renal transplant directed at class II donor HLA mismatches which predicts kidney graft loss.
Patient survival decreased at 5 years post-transplant in DSA positive patients compared to DSA negative patients.
In liver transplantation, it is difficult to identify early AMR due to
– lack of clear clinical , histology cal and immunohistological cretria for diagnosis of AMR.
– nonspecific clinical and pathological findings of cholestasis similar to AMR.
Recipients that maintain positive crossmatch are at high risk of AMR.
Studies shown as regard to relation between DSA and chronic rejection using MFI ,performed class I antibodies more determental to graft survival than class II antibodies.
Pancreatic transplantation, there is association between post transplant DSA and decreas graft survival and increase incidence of rejection.
Long term pancreatic graft survival is inferior to survival of other solid organ as diagnosis of pancreatic is clinically complex.
Presence of pre-transplant DSA in islet cell transplantation associated with poor outcomes after transplantation.
In lung transplantation, presence of anti-HLA antibodies associated with bronchitis obliterating syndrome which cause poor prognosis and short graft survival.
In cardiac transplantation , cardiac allograft vasculopathy ,primary cause of death in long term heart transplant survivors due to complement activation and fixation in graft endothelium .
Presence of C1q+ DSA after transplantation had AMR at next biopsy ( have C4d deposition) suggests that DSA monitoring is effective in predicting AMR .
C1q assay is designed to detect immunoglobulin G IgG which fix complement.
Post transplantation monitoring ,a lot of patients who were DSA negative pre-transplant develop DSA post- transplant.
Serial monitoring of alloantibodies post-transplantation help in early diagnosis of chronic rejection and early identification of patients who are at risk of rejection due to non-compliance with immunosuppressive medication.
SAB luminex is highly sensitive to detect DSA even with low level which can put patient in risk of rejection.
1. OPTN & SRTR 2010 Annual Data Report. http://www.srtr-org/annual_reports/2010 Accessed 20 May 2012.
2. Sutherland SM et al. Complement-fixing donor-specific antibodies identified by a novel C1q assay are associated with allograft loss. Pediatric Transplantation 2011.
3. Dunn TB, et al. Revisiting traditional risk factors of rejection and graft loss after kidney transplantation.
American Journal of Transplantation 2011.
4. Colvin RB, et al. Antibody-mediated organ allograft rejection. National Review of Immunology 2003; 5(10): 807-817.
5. Kaczmarek I, et al. Donor-specific HLA alloantibodies: long-term impact on cardiac allograft vasculopathy
and mortality after heart transplant. Experimental and Clinical Transplantation 2008; 6: 229-235.
6. Issa N, et al. Transp ation 2008: 86(5): 681-685.
7. Terasaki, et al. Humoral theory of transplantation. American Journal of Transplantation 2003; 3: 665-673.
8. Kimball PM, et al Surveillance of alloantibodies after transplantation identifies the risk of chronic
rejection. Internal Society of Nephrology 2011 ; 79: 1131-1137.
9. Lefaucheur, et al. Clinical relevance of preformed HLA donor-specific antibodies in kidney
transplantation. American journal of transplantation : official journal of the American Society of Transplantation and the American Society of Transplant Surgeons 2008; 8(2): 324-331.
10. Wiebe C, et al Evolution and clinical pathologic correlations of de novo donor-specific HLA antibody post kidney transplant. American Journal of Transplantation 2012; 12: 1157-1167.
11. Yabu JM, et al. C1q-fixing human leukocyte antigen antibodies are specific for predicting transplant glomerulopathy and late graft failure after kidney transplantation. Clinical and Translational Research 2011; 91 (3):342-347.
Nadia Ibrahim
3 years ago
1. In your own words, summarise the role of anti-HLA Antibodies in Transplantation.
AMR
Anti-Human Leukocyte Antigen (HLA) DSA are either preformed( with blood transfusion, previous transplant, or pregnancy or Denove And are associated with AMR, graft failure, poor graft and patient survival.
preformed DSAs are usually associated with early acute AMR, chronic rejection, and subclinical rejection (without immediate apparent graft dysfunction). on the other hand Denovo DSAs are associated with early and late acute AMR, chronic and subclinical AMR
development of chronic renal failure isa leading cause of renal allograft failure.(1) Chronic Rejection due to de novo DSA from the start or complicating acute AMR, Patients with preformed DSA and those who develop de novo DSA are at an increased risk of having chronic rejection.
The early identification and subsequent removal of clinically harmful DSA associ- ated with AMR, both pre- and post-transplant, may prevent allograft loss (1)
In KTx numerous studies demonstrated that de novo DSA against Class II donor HLA mismatches development , is associated with poor out-comes (2) Liver Transplantation: DSA was an independent predictor of poor patient survival and was associated with AMR (3)
Denovo DSA associated with chronic rejection , with the Anti class I DSA beingare more significant with negative outcomes. Pancreas Transplantation:
post-transplant denovo DSA increased incidence of rejection and decreased graft survival. Islet Cell and Multi-Visceral Transplantation
pre-transplant DSA is associated with poor outcomes postransplant. Lung Transplantation
DSAs are associated with a higher prevalence of BOS (Bronchiolitis Obliterans Syndrome) with poor graft and patient survival. 2. How would you monitor DSA post-transplantation? Serial monitoring of DSA is more valuable than single-point testing, DSA monitoring 1) C1q assay
Some of the DSAs are complement fixing (Ig G) , others are non complement fixing not causing rejection, C1q (+) used in monitoring of complement fixing DSAwere significantly significantly associated with graft rejection and more likely to have C4d deposition in biopsy. 2)Luminex®-based single-antigen beads (SAB)
Value :
1) discrimination between donor-specific and non-donor-specific antibodies
2) highly sensitive thus detecting low level DSA which can still put patients at risk for rejection
3) detect Changes in DSA specificities or the appearance of new DSA that predect an early rejection process Post-transplantation Monitoring
1) predicting AMR
2) Early identification of DSA through routine monitoring, helps the early initiation of anti-hu-
moral therapy as a result clearance of DSA and improvement of the overall survival rates.
3) Serial facilitate early diagnosis of chronic rejection.40
4) identification of patients at risk for rejection due to insufficient immunosuppression due to nonadherence to immunosuppressivemedications
5) adjustment of immunosuppressive therapy post-transplant.
References:
(1) Kimball PM, et al Surveillance of alloantibodies after transplantation identifies the risk of chronic rejection. Internal Society of Nephrology 2011 ; 79: 1131-1137.
(2) Fotheringham J, et al Natural history of protienuria in renal transplant recipients developing de novo human leukocyte antigen antibodies. Clinical and Translational Research 2011; 91 (9): 991-996.
(3) Kozlowksi T, et al Liver allograft antibody-mediated rejection with demonstration of sinusoidal C4d staining and circulating donor-specific antibodies. Liver Transplantation 2011; 17: 357-368.
Nasrin Esfandiar
3 years ago
In spite of potent immunosuppression long-term graft survival has not improved recently due to DSAs resulting in AMR.
To prevent graft loss,determining preformed or de Novo DSA is helpful. Acute AMR isoften caused by preformed DSAs but late or chronic AMR by denov DSAs.Another type of AMR is subclinical AMR which is not associated with immediate graft dysfunction,could deteriorate long-term graft functio. Subclinical AMR could be seen with both types of DSA (preformed or de Novo ) and maybe C4d isnegative and is related to non- adherence. De novo DSAs could progress from subclinical injury with pertubular capillaricapillaries +/- c4d, glomerulitis to IFTA +/- transplant glomerulopathy with increased creatinine and proteinuria, causing graft loss. They are usually against class II of honor HLAs .C1q (+)DSAS are capable of fixing complement so theyare 6times more harmful .The most sensitive method for DSA monitoring is luminex SAB .Early detection and treatment of de Novo DSAs results in decline in their titer by90%
Wael Hassan
3 years ago
-The primary cause of graft loss is late anti-body mediated rejection (AMR). – DSA was defined as preformed antibodies present in the recipient’s serum against donor’s HLA antigens, these formed pre-transplant as a result of a sensitization event (blood transfusion, previous transplant, or pregnancy). – Recently, there is a trend toward monitoring for the post-transplant development of antibodies directed against donor-specific HLA class I and class II mismatches. The DSAs whether detected pre- or post-transplant, if not treated, increase the risk of graft loss and/ or rejection. Because DSA attacks the endothelium of the allograft causing AMR.
–DSAs responsible for AMR are either preformed DSA which largely causes early acute AMR rejection and De novo DSA which, is responsible mainly for a late AMR and to a lesser extend to early AMR. AMR significantly lower graft survival. -DSA can cause subclinical antibody-mediated rejection (SAMR) which associated with poor long-term graft function. SAMR is caused by preformed DSA and some of which are C4d stain negative. -the range of dnDSA post-transplant is 24% to 62% with the highest level in liver transplantation. -the graft survival decrease with the presence of anti-HLA II antibodies and their level also impact the graft survival, as a high level is associated with low graft survival. C4d stain TG has the lowest graft survival as compared with C4d negative.
DSA is Predictive of Lower Patient Survival:
Not only the graft survival but also the patient survival affected by the presence of anti-HLA antibody. DSA was an independent predictor of poor patient survival
-in liver transplantation there is suggestions to diagnose AMR in liver transplant, based on the presence of DSA in the recipient serum. Preformed class I antibodies was found to be more determined to graft survival than class II antibodies. Detection of de novo DSA in the first year put the patient at high risk of graft rejection, especially in C4d positive recipients. -in a study reported by Yabu et al., the presence of C1q (+) DSA 6 times more likely to lose their grafts due to allograft rejection and more likely to have C4d positivity on biopsy, than patients with C1q (-) DSA. -serial monitoring of these antibodies helps diagnosis of chronic rejection. Routine monitoring of DSA may provide early identification of patients at risk for rejection and may be useful in dose adjustment of the immunosuppressive therapy. Early identification of DSA can predict AMR occurrence, allowing for initiation of specific treatment sooner, to clear these DSA and ultimately improve graft survival. – (SAB) is a highly sensitive tool, can discriminate between donor-specific and non-donor-specific antibodies. It has the advantage to detect a low level of DSA that can increase the risk of rejection and can detect new DSA and changes in DSA. –
Ahmed mehlis
3 years ago
The Role of anti-HLA Antibodies in Transplantation?
● in pre transplantation in the past the concept of hla ab was precisely to sensitization but nowadays it is concerned with any antigen in doner to which patient devolp ab
the presence of antibodies
directed against antigens expressed on donor organs, when not treated clinically, results in an immune attack on the transplanted organ, and increases risk of graft
loss and/or rejection. DSA attacks the endothelium of the allograft, resulting in subsequent AMR.4,5 The progression of DSA development and thecorresponding clinical events compound to damage the allograft, resulting in chronic changes over time that ultimately compromise graft function and survival.
●How would you monitor DSA post-transplantation?
C1q assay may prove to be important in optimizing post transplant care.
Luminex-SAB is the most sensitive allow for a precise, highly sensitive determination of a patient’s antibody profile. This makes discrimination between donor-specific and non-donor-specific antibodies possible.
Other methos fc , elisa and cdc .
Wessam Moustafa
3 years ago
Although there is great advances in renal transplantation yet the long term graft survival is sub optimum , AMR is a major cause of post transplant graft loss .
DSAs which was historically defined as pre formed circulating anti HLA antibodies, has a main role in development of AMR .
DSAs could develop post transplant and are called denovo DSAs and are associated with higher rates of graft failure .
Presence of DSAs doesn’t only affect graft survival , but also patient survival .
Rejection caused by DSAs may be subclinical , hyperacute or acute AMR .
The detection of anti-HLA antibody in transplant recipients allows the clinician to better predict AMR in
the post- transplant period .
Not all DSAs are clinically relevant for organ transplantation, mainly the complement fixing antibodies are clinically important.
C1q assays, detect the complement fixing DSAs before tx .
Post transplant monitoring of DSAs is essential as it may help prediction of AMR , allow adjusting IS of at risk patients ,allowing early clearance of DSAs improving survival of graft .
Luminex based SAB is the best for DSAs monitoring post transplant.
The frequency of monitoring is based upon patient risk
Early identification and elimination of DSAs significantly improves survival of graft and the patient
Jamila Elamouri
3 years ago
the role of anti-HLA antibodies in transplantation
Although there are significant improvements in post-transplant care, maintaining long term graft function is a big challenge. The primary cause of graft loss is late anti-body mediated rejection (AMR). In the past, DSA was defined as preformed antibodies present in the recipient’s serum against donor’s HLA antigens, these formed pre-transplant as a result of a sensitization event (blood transfusion, previous transplant, or pregnancy). Recently, there is a trend toward monitoring for the post-transplant development of antibodies directed against donor-specific HLA class I and class II mismatches. The DSAs whether detected pre- or post-transplant, if not treated, increase the risk of graft loss and/ or rejection. Because DSA attacks the endothelium of the allograft causing AMR.
In order to prevent allograft loss, identification and subsequent removal of harmful DSA that cause AMR in both pre-and post-transplant courses. Sold-phase assays are both sensitive and specific tools for the accurate identification of DSA. The Spectrum of Antibody-Mediated Rejection:
DSAs responsible for AMR are either preformed DSA which largely causes early acute AMR rejection and De novo DSA which, is responsible mainly for a late AMR and to a lesser extend to early AMR. AMR significantly lower graft survival. Subclinical Antibody-Mediated Rejection:
DSA can cause subclinical antibody-mediated rejection (SAMR) which, may not be associated with an impairment of graft function. But, it is associated with poor long-term graft function. SAMR is caused by preformed DSA and some of which are C4d stain negative. Non-adherence to immunosuppressive drugs are De Novo DSA in Post-Transplant Solid Organ Transplant Recipients
The range of dnDSA post-transplant is 24% to 62% with the highest level in liver transplantation.
In cardiac allograft, the development of dnDSA has been associated with decreased graft survival either during or after the 1st year post-transplantation.
In kidney transplant recipients, DSA develops mainly against Class II donor HLA mismatches. It is associated with poor outcomes.
DSA is Predictive of Lower Graft Survival:
The development of HLA antibodies predict graft survival, and as the time elapsed post-transplant the risk of AMR increases with the presence of anti-HLA-Class II antibodies.
Effect of DSA on Renal Allograft Survival:
Renal graft survival is lower in the presence of de novo DSA when compared with those without de novo DSA. The Effect of Transplant Glomerulopathy (TG) on Renal Allograft Survival:
The graft survival decrease with the presence of anti-HLA II antibodies and their level also impact the graft survival, as a high level is associated with low graft survival. C4d stain TG has the lowest graft survival as compared with C4d negative.
DSA is Predictive of Lower Patient Survival:
Not only the graft survival but also the patient survival affected by the presence of anti-HLA antibody. DSA was an independent predictor of poor patient survival
Liver Transplant:
The diagnosis of an early AMR in liver transplant recipients is difficult, due to the lack of clear criteria for diagnosis as well, the result of crossmatch at the time of transplantation. recently, there is suggestions to diagnose AMR in liver transplant, based on the presence of DSA in the recipient serum. Preformed class I antibodies was found to be more determined to graft survival than class II antibodies. Detection of de novo DSA in the first year put the patient at high risk of graft rejection, especially in C4d positive recipients.
Pancreas Transplantation:
The development of post-transplant DSA is significantly associated with poor outcomes. It is considered an independent risk factor for graft survival by many studies.
Islet Cell and Multi-Visceral Transplantation:
The presence of preformed DSA put the recipient at high risk of rejection, so monitoring of DSA in these patients is a valuable diagnostic tool for early diagnosis and treatment of acute rejection.
Lung transplantation:
Bronchiolitis Obliterans Syndrome (BOS) is a serious complication of lung transplantation leading to shorter graft survival. Its occurrence is strongly associated with the presence of anti-HLA antibodies. The presence of these antibodies precede the diagnosis of BOS by about 1.1 years.
Cardiac Transplantation:
Cardiac allograft vasculopathy (CAV) is the primary cause of death. The presence of DSA can result in complement activation and fixation on the graft endothelium, leading to graft loss and death.
The Future of DSA Monitoring: Effect of C1q DSA on Allograft Survival
Anti-HLA antibody monitoring can help the clinician to better predict AMR in the post-transplant patient. Complement fixing antibodies are more relevant to organ rejection and their detection important in order to treat transplant patients properly. A novel C1q assay perfectly detects complement-fixing antibodies and in combination with other methodologies can define the patient’s immunologic profile. Patients with C1q (+) DSA after transplant had AMR at the next biopsy, suggesting DSA monitoring is effective in predicting AMR.
In a study reported by Yabu et al., the presence of C1q (+) DSA 6 times more likely to lose their grafts due to allograft rejection and more likely to have C4d positivity on biopsy, than patients with C1q (-) DSA.
Post-Transplantation Monitoring:
Many DSA negative recipients develop DSA within 2 years post-transplantation. serial monitoring of these antibodies helps diagnosis of chronic rejection. Routine monitoring of DSA may provide early identification of patients at risk for rejection and may be useful in dose adjustment of the immunosuppressive therapy. Early identification of DSA can predict AMR occurrence, allowing for initiation of specific treatment sooner, to clear these DSA and ultimately improve graft survival.
Graft survival in recipients in whom DSA persist is worse than those who had cleared the DSA. Why monitor DSA post-transplantation:
1- Allograft survival can be predicted.
2- > 40% of kidney transplant recipients with AMR develop transplant glomerulopathy.
3- Recipients diagnosed with transplant glomerulopathy have a 5-year graft survival rate less than 50% from the time of diagnosis.
4- Early antibody developers have less graft survival.
5- De novo DSA in cardiac transplant recipients are highly associated with decreased survival especially worse in those with persistent DSA.
6- Non-adherence to immunosuppression is a major factor in the development of de novo DSA
7- Inadequate immunosuppression contributes to de novo DSA and AMR that can be C4d negative
Why monitor with single bead antigen:
Luminex based single-antigen beads (SAB) is a highly sensitive tool, can discriminate between donor-specific and non-donor-specific antibodies. It has the advantage to detect a low level of DSA that can increase the risk of rejection and can detect new DSA and changes in DSA. Optimizing DSA Monitoring Strategies: DSA monitoring is increasingly suggested as a standard of care in transplantation. the frequency of monitoring will be patient-specific according to individual risk for AMR. Serial monitoring is more valuable than a single monitoring test. Conclusion:
The transplantation field show several advancements since its beginning. Most recently, many data indicate the use of DSA monitoring in post-transplantation as an important tool in the management of these patients. And the routine monitoring of DSA in the post-transplant cases offers promise in long term graft and patient survival
Summary :
Detection of Anti-HLA antibodies in the recipient serum pre-transplantation affect the decision of transplantation, precede or not with that donor. Risk classification of the recipient (rejection risk). Choice of immunosuppression protocol either the induction or the maintenance therapy. And the use of desensitization protocol.
Post-transplantation monitoring of the DSA can predict rejection. Offer therapy to clear these DSA can improve graft survival. Help in immunosuppression dose adjustment.
with the advanced Luminex assay more precise detection of DSA become possible
Mohammed Sobair
3 years ago
Though there’s significant improve improvements in post-transplant care, long term graft
function is less than optimal.
In the United States, adjusted 10 year allograft survival rates for deceased and living
donor kidney transplants are only 40.8% and 57.9%, respectively.
AMR leading to Late stage graft failure, secondary to antibody is a main cause of poor
graft survival.
Patient survival is also significantly decreased at 5-years post-transplant in DSA positive
patients compared to non DSA patient.
Monitoring of DSA either do novo or primary is important in transplant.
DSA, when not treated clinically, results in an immune attack on the transplanted organ,
and increases risk of graft loss and/or rejection.
DSA attacks the endothelium of the allograft, resulting in subsequent AMR.
Anti-HLA antibodies contribute to the development of chronic renal failure, the leading
cause of renal allograft failure.
The early identification and subsequent removal of clinically harmful DSA associated
with AMR, both pre- and post-Transplant aid in salvage of graft.
Early acute process: often lead to acute rejection
Chronic AMR: Patients with preformed DSA and those who develop de novo DSA are at an increased risk of having chronic rejection.
Subclinical antibody mediated rejection:
DSA may also develop without an immediate impairment of graft function. This type of
rejection, or subclinical antibody mediated rejection (SAMR), has been reported to have
an impact on long-term graft dysfunction and deterioration.
The development of de novo donor-specific HLA antibodies post-transplantation has
been associated with higher graft failure rates. The range of dn DSA is 24% to 62% with
the highest presence in post liver transplant recipients.
Monitoring DSA :
Research has suggested that the evaluation of the C1q assay provides a further layer of
immunologic antibody information that may prove to be an adjunct in optimizing post-
transplant care.
kidney transplant recipients with C1q (+) DSA were nearly 6 times more likely to lose
their grafts than those with C1q (-) DSA.
routine monitoring of DSA may provide early identification of those patients at risk for
rejection due to insufficient immunosuppression as a result of poor compliance with
immunosuppressive therapy. DSA monitoring may be useful in the adjustment of
immunosuppressive therapy post-transplant.
Why monitoring?
10 years graft Survival is less in early antibody developer than late .
40%develope TG.
Patient with TG experienced 5-year graft survival rates less than 50% from the time of
diagnosis.
Many patient developed de novo DSA secondary to non-adherence to
immunosuppressive therapy. Insufficient immunosuppression may contribute to the
development of de novo DSA and AMR secondary to misclassifications based on C4d
negativity.
The use of Luminex® SABs a provides a number of advantages, including:
• The presence of low-level DSA can put patients at risk for rejection
• Changes in DSA or the appearance of new DSA specificities may reveal an early
rejection process.
Optimizing DSA Monitoring Strategies:
Choosing a monitoring frequency based on a patient’s individual risk of developing AMR
post-transplant will be the most efficient and clinically relevant strategy.
Serial monitoring of DSA is more valuable than single measure.
Post transplantation Group :
(a) High-risk patients (i.e., desensitized or DSA positive/XM negative) should be
monitored by measurement of DSA and protocol biopsies in the first 3 months after
transplantation.
(b) Intermediate-risk patients (history of DSA but currently negative) should be monitored
for DSA within the first month. If DSA is present, a biopsy should be performed.
(c) Low-risk patients (no sensitized first transplantation) should be screened for DSA at
least once 3 to 12 months after transplantation. If DSA is detected, a biopsy should be
performed.
In all three categories, the recommendations for subsequent treatment are based on the
biopsy results.
Ban Mezher
3 years ago
Anti HLA Ab are formed against HLA Ag during pregnancy, blood transfusion or previous transplantation. It associated withy increase risk of hyper acute & acute antibody rejection. So presence of preformed DSA associated with decrease the chance of obtaining compatible donor. Anti HLA Abs can be directed to private specificities (HLa-A1) or public specificities ( Bw6).
Nowadays anti-HLA DSA considered the most significant biomarkers for prediction of graft failure. The exact characterization of anti-HLA DSA as complement binding capacity & IgG subclasses can add more benefit for prediction of graft outcome. Consensus guidelines in 2013 for post transplant screening for DSA recommend the following:
all patients in early post transplantation period ( the time depend on risk of patients for AMR (a) low risk patients should had at least once DSA measurement in 3-12 months after transplantation, (b) intermediate risk ( -ve DSA at time of transplantation, but had previous DSA) screening done in first month post transplantation. Additional testing not recommended unless there will be change in immunosuppression, suspicion of non adherence, graft dysfunction or transferring the patient outside his center.
if DSA occur at any time, graft biopsy should be done
in high risk patients & in sensitized cross-match +ve ( very high risk patients, biopsy is recommended in first 3 months post transplantation in addition to DSA monitoring.
After I year post transplantation, measuring of DSA is not routinely done unless there is graft dysfunction, non adherence, or change in immunosuppression.
References:
Biglietti D., Loupy A., Vernerey D., et al. Value of Donor-specific Anti-HLA Antibody Monitoring and Characterization for Risk Stratification of Kidney Allograft Loss. J Am Soc Nephrol. 2017;28:702-715.
Morath C., Opelz G., Zeier M., et al. Clinical Relevance of HLA Antibody Monitoring after Kidney Transplantation Journal of Immunology Research. 2014.
Vinicius M., Zollner R., and Mazzali M. Renal transplant patients with preformed anti-HLA antibodies: early biopsy findings and clinical outcomes. Braz.J.Nephrol. 2020, 42(2):201-210.
fakhriya Alalawi
3 years ago
1- The presence of antibodies directed against antigens expressed on donor organs attacks the immune system on the transplanted organ and increases the risk of graft loss or rejection. In addition, DSA attacks the endothelium of the allograft, resulting in subsequent AMR. Repeated attacks of such alloantibody-mediated injury result in distinct changes in the microvasculature of the allograft and development of chronic rejection and have been associated with a higher graft failure rate.
The development of de novo antibodies during and after the first year post-transplant has been shown to significantly reduce the 15-year graft survival in cardiac allografts recipients. Moreover, it was associated with a higher incidence of sub-clinical AMR, leading to long-term graft dysfunction. Similarly, de novo DSA is associated with poor outcomes in renal transplant patients, liver, lungs (leading to Bronchiolitis Obliterans Syndrome (BOS)), and pancreas recipients.
2- DSA Monitoring: Many transplant recipients are DSA (-) pre-transplant and develop DSA post-transplant, typically within the first two years. Serial monitoring of anti-HLA antibodies in transplant recipients may facilitate early diagnosis of chronic rejection. Moreover, it is of great value in adjusting immunosuppressive therapy post-transplant and initiating anti-humoral therapy once DSA is detected, allowing for early clearance of DSA, hence improving the overall allograft survival rates. Serial monitoring of DSA is more valuable than single-point testing.
A novel C1q assay is designed to detect immunoglobulin G (IgG) antibodies that can fix and activate complement. C1q (+) DSA estimation had proven its high efficacy in several studies in predicting AMR, before allograft damage has been ensued, in several publications, including pediatric heart transplant recipients and kidney transplant recipients. Patients with C1q (+) DSA were significantly more likely to have C4d deposition on biopsy. Additionally, patients with C1q (+) DSA were nearly six times more likely to lose their grafts than those with C1q (-) DSA.
Mujtaba Zuhair
3 years ago
De novo DSA is associated with poor graft survival. it can lead to early acute AMR or can lead to chronic AMR and graft failure.
DSA can lead to subclinical rejection without immediate graft dysfunction but on the long term can lead to transplant glomerulopathy and graft failure.
So the presence of DSA is associated with lower patient and graft survival.
monitoring for DSA is important to detect them early before graft damage so we can optimize immunosuppression and emphasize on adherence to immunosuppressive drugs.
Low risk patients should be monitored at least once during 3 -12 months post transplant and then once a year. for those with higher risk should be monitored more frequently.
Tahani Hadi
3 years ago
B cells and plasma cells activation cause DSA activation which is the leading cause of AMR by activation and binding to HLA and non HLA Ab leading to transplant glomerulopathy and initiation of AMR with it’s different forms: hyperacute, early and late acute AMR and chronic ABMR.
Most sensitized patients have DSA level pretransplant known as performed DSA occurs due to different causes the other type is denovo DSA occurs late after transplantation responsible for late acute AMR with poorer outcome than the performed DSA,DSA level can be affected by type of induction and immunosuppressive protocols this will also cause better graft function and prevention of rejection.
DSA cause damage to the graft either by complement activation, C1q binding or direct effects on endothelial cells and Ab mediated cytotoxicity, all these mechanisms are affected by DSA class ,strength of C1q and IgG subclasses(IgG3 is most effective and capable to bind to C1q and can cause early graft loose), studies showed the effect of C1q positive DSA on graft loss and acute rejection with C4D deposition.
DSA should be monitored for early detection and treatment of rejection most patients should be monitored every 2 _3 months in the first year post transplant then annually but in sensitized patients more frequent monitoring and graft biopsy is mandatory in risky patients .
DSA monitoring help to:
improve graft outcome
adjust immunosuppressants especially in non compliance patients
Detect low DSA titer even with absence of graft dysfunction
Detect new DSA or change in the level of preexisting DSA.
Reference
_clinical trials.gov. .(2021,March 9).Donor specific Anti_HLA antibodies monitoring in kidney transplant recipient. Retrieved from U.S.national library of medicine.
_ journal of immunology research. (2014,October 13).clinical relevance of HLA antibodies monitoring after kidney transplant. From Hindawi,Mario cleric.
Mohamed Fouad
3 years ago
The Anti HLA antibodies either preformed circulating antibodies or de novo DSA against HLA class I and class II present in the recipient’s immune system have a crucial role in long term graft survival. These antibodies directed against antigens expressed on donor organs, if not treated by desensitization results in an immune attack on the transplanted organ and increases risk of graft loss and rejection. DSA attacks the endothelium of the allograft, resulting in subsequent ABMR. Frequent attacks of ABMR resulting in chronic changes over time that ultimately impact graft function and survival.It has shown that up to 96% of rejected allografts develop some degree of DSA.
Sub-Clinical Antibody Mediated Rejection
Histological evidence of ABMR can be present without change in serum creatinine that due to subclinical Prescence of DSAs and this type of rejection reported to have an impact on long-term graft dysfunction. Typically, non-adherence to immunosuppressive therapy is associated with the histological finding reflecting the high frequency of de novo DSA.
De Novo DSA in Post-Transplant Solid Organ Transplant Recipients
De novo antibody production may cause subclinical ABMR that is associated with long- term graft dysfunction. Negative outcomes can take several years to occur after de novo antibody production. DSA is Predictive of Lower Graft Survival and risk of Transplant Glomerulopathy development depends on anti-HLA-II levels.
DSA is Predictive of Lower Patient Survival
There is a strong association between presence of of anti-HLA antibody and patient survival
Effect of C1q DSA on Allograft Survival:
Since not all anti HLA antibodies can fix complement, A novel C1q assay designed to detect immunoglobulin G (IgG) antibodies capable of fixing complement has been studied in the post-transplant setting. The presence of C4d negative ABMR biopsiesmake the C1q assay more important to get information regarding complement activation in ABMR process. Some studies have reported that C1q DSA have been associated with higher incidence of AMR and graft loss. In a study reported by Yabu et al., kidney transplant recipients with C1q (+) DSA were nearly 6 times more likely to lose their grafts than those with C1q (-) DSA.
Post-transplantation Monitoring
It is known that the antibodies need a long time to produce the chronic vascular changes that can result in graft failure. So the serial monitoring of HLA antibodies following transplantation may facilitate early diagnosis of chronic rejection and will guide to patients at risk for rejection due to insufficient immunosuppression as a result of poor compliance with immunosuppressive therapy.
Why Monitor With Single-Antigen Beads?
The fast-growing methods for detecting anti HLA antibodies making Luminex SABs is most sensitive method to detect anti HLA antibodies and being as part of a comprehensive monitoring program which can discriminate between donor-specific and non-donor-specific antibodies.
Optimizing DSA Monitoring Strategies
The frequency of post-transplant monitoring will be patient specific. Choosing a monitoring frequency based on a patient’s individual risk of developing AMR post-transplant will be the most efficient and clinically relevant strategy.
Esmat MD
3 years ago
Detected pre and post transplantation DSA is associated with an increased risk of rejection and graft loss.
DSA attacks to the graft endothelium of allograft and results in AMR and over time leads to chronic changes that eventually comprise graft survival.
It has shown that up to 96% of rejected allografts develop some degree of DSA.
Since the presence of anti HLA antibodies correlates with kidney graft failure, early recognition of harmful DSA and removal of them may prevent allograft loss.
The spectrum of AMR
AMR is often either acute, resulting from anamnestic response and preexisting DSA or late or chronic due to de novo DSA (dn DSA).
Patients with performed DSA are at increased risk of acute AMR that is related to significantly lower graft survival. Chronic rejection, a leading cause of graft loss, is associated with both performed and de novo DSA.
Subclinical AMR
DSA can also be associated with subclinical AMR that has a deleterious impact on long term graft dysfunction. Negative outcomes can take several years after production of dnDSA.
Microcirculation inflammation that is more common in late kidney biopsies may reflect the high frequency of de novo DSA, although it is also a frequent finding with performed DSA.
De novo DSA
The development of dnDSA has been associated with higher graft loss. dnDSA is more frequent in post liver transplant recipients.
Development of DSAs after one year has been associated with worse graft survival compared to development of dnDSA during the first year after cardiac transplantation.
In kidney transplant patients, dnDSA predominantly directed at class II HLA, and is associated with poor outcomes.
The risk of chronic AMR increases with the presence of anti-class II HLA DSAs.
In addition to the impact of dnDSA on graft survival, the significant association of them with recipients’ survival has also been demonstrated.
In liver transplant patients, the presence of DSAs is associated with AMR and rejection, particularly class I antibodies. Furthermore, DSA is associated with negative outcomes, indicating that AMR may contribute to interlobular bile duct loss.
In pancreas transplantation, development of post-transplant DSAs has been associated with poor outcomes, and may be utilized as an independent risk factor for graft survival.
In the pancreas, islet cell transplantation, and multivisceral transplantation, the presence of DSAs indicates a high risk of rejection. Thus, DSA monitoring is a valuable tool for early diagnosis and treatment of AMR.
In lung transplantation, DSAs are associated with a higher prevalence of BOS, and it is crucial to detect DSA sooner.
In cardiac transplantation, circulating DSAs predispose patients to accelerate cardiac allograft vasculopathy, graft loss and death.
The effect of C1q assay
Since not all DSAs are complement fixing and may not be relevant to organ rejection, the C1q assay has been designed to detect IgG antibodies capable of fixing complement. The role of complement fixation, as detected by C4d staining in predicting AMR, is not widely accepted. The C1q assay may provide more immunological information for optimizing post-transplant care. Some studies have reported that C1q DSA have been associated with higher incidence of AMR and graft loss and the presence of C4d deposition biopsy.
Post-transplantation DSA monitoring
Many recipients that are DSA-, may develop DSA post-transplant, especially in the first 2 years after transplantation. Since it may take months to years that DSA production led to chronic vascular change, monitoring and early detection of DSAs may provide early identification of those patients at risk for rejection and with appropriate therapy may improve the overall survival rate. Persistent DSAs are associated with the worst survival.
Survival in early antibody developers (<1year) is better than late antibody developer.
More than 40% of kidney transplant recipients with AMR develop transplant glomerulopathy, and five-year survival in recipients with transplant glomerulopathy was less than 50%.
Non adherence and insufficient immunosuppression may contribute to development of dnDSA.
Luminex based SAB
SAB is a precise and very sensitive assay for detection of DSA, and provides discrimination between donor-specific and non-donor specific antibodies with a number of advantages: detection of a low level of DSA, detection of changes in DSA or the appearance of a new DSA that may reveal an early rejection process.
Optimizing DSA monitoring
Routine post-transplant DSA monitoring has been recognized as a standard of care practice, and monitoring frequency should be individualized based on patient’s individual risk of developing AMR. Serial monitoring of DSA is more valuable than single-point testing.
saja Mohammed
3 years ago
In your own words, summarize the role of anti-HLA Antibodies in Transplantation.
How would you monitor DSA post-transplantation?
Despite the improvement in the organ transplant still graft survival hampered by antibody mediated rejection (AMR), still the 10-year survival of LD and DD only 56%, 44% respectively based on the US-data registry. In another large cohort study reported 25% of recipients developed DSA post transplantation also performed DSA found in the range of 24-68% of transplantation and highest with liver transplantation.
Performed DSA more in sensitized patients (previous transplantation, blood transfusion, pregnancy), DSA can lead to subclinical acute rejection with normal allograft function (SMAR), which can impact the long-term graft survival and need years to show the effect on the graft, especially in recipients with poor compliance with IS.
Performed DSA For both class1, class11 can cause AMR, class1 HLA, in particular IgG2, IgG4 abs with typical endothelial injury and microvascular inflammation acute AMR and associated with poor graft survival while class11, Dn DSA associated with late and chronic ABMR, especially C4D+ TG which associated with worst graft survival.
15 years cardiac allograft survival in the presence of ds DSA is reduced to 52% in the first year ,40% after 1 year of TX, also associated with lower 5-year patient survival.
Pancreatic, lung and multi-visceral organ transplant had inferior graft survival with the performed DSA with increased risk of AMR.
In liver transplant performed anti- class 1 DSA in the first year associated with poor graft survival as compared with class2 and development of DSA after first year usually associated with chronic rejection, DSA+/diffuse C4d+ patients had a significantly higher frequency of ACR, with steroid resistant rejection, and bile duct injury
Both complement fixing DSAs like C1q associated with ABMR, and associated with 6-fold risk of graft loss, C1q -assay can help in predicting AMR with C4D staining is important for the diagnosis of AMR.
Post-transplantation Monitoring:
The incidence of chronic AMBR was not significantly dependent on the MFI value (Schinstock et al., 2017)also not all DSA lead to tissue damage, DSAs post-transplant may stays for years with stable graft function, Moreover, problems such as bead saturation, shared epitope, and prozone effect can lead to MFI values that differ from DSA levels, so the use of single antigen flow bead (SAFB) with antibody titration methods its more accurate to assess DSA intensity, (Velidedeoglu et al.,2018; Schinstock et al., 2020).
routine monitoring of DSAshould be considered as standard of care post transplantation as it helps with oyjer clinical indicators like creatinine and protienuria in early diagnosis of AMR, the frequency of DSA monitoring should be patient specific, those with low risk need less frequent monitoring while moderate and high-risk patients need more frequent assays (1,3,6,12 months ) post Tx then every year at any point patient had acute graft dysfunction with history ofpoor compliance with IS medication should perform the DSA assay with graft biopsy and treat accordingly
Patients with rising dn DSA level with in first 3 months post TX, should go for graft biopsy ,Sensitized patients with pre-transplantation DSAs,preferred frequent monitoring and protocol biopsy 3, 12 months.
Promising noninvasive molecular biomarkers:
still under investigation and need validation by large cohorts trails including:
1-IFN-γ enzyme-linked immunosorbent spot assay
2- donor-derived cell-free DNA (dd-cfDNA) assay. this test was validated for Acute Rejection diagnosis in Kidney Transplant Recipients (DART) study which included patients with active ABMR, chronic active ABMR, or TCMR With a cutoff of 1.0%, (Bloom et al., 2017). The combination of dd-cf-DNA with DSA monitoring increase the sensitivity and specificity for the diagnosis of Active AMBR, TCMR.
References:
1- Up to date medicine, DSA monitoring post transplantation
2- Therapies for Chronic Allograft Rejection: In Young Kim and Daniel C. Brennan *
Department of Internal Medicine, Johns Hopkins School of Medicine, Baltimore, MD, United States, published: 15 April 2021.
Theepa Mariamutu
3 years ago
Donor Specific Antibody Monitoring
Role of Anti-HLA Antibodies in Transplantation
• Adjusted 10 year allograft survival rates for Deceased and living donor kidney transplantation in US are only 40.8% and 57.8%
• Anti-HLA is preformed circulating antibodies present in the recipient immune system which occurs due to sensitising phenomena such as blood transfusions, pregnancy and previous solid organ transplantation
• DSA and form against class 1 or 2
• DSA attacks the endothelium of allograft results in AMR
Spectrum of AMR
• Can occur as an early acute process – due to rapid response
• late and chronic process due to DnDSA
Subclinical Antibody mediated rejection
• occurs without an immediate deterioration of graft function
• have an impact on long term graft dysfunction and deterioration
• Lousy et al- happens winning 3. Months to 3years while chronic lesions steadily increases and significantly over 3 years
• micro circulation inflammation is commonly seen after 1 year kidney transplantations
• Non adherence to meds will have C4d stain negative SAMR
• dnDSA in post kidney transplantation usually directed against HLA class 2 and associated woth poor graft function
Prediction of lower graft survival
• the risk of developing chronic rejection leading to AMR increases with presence of Class2 antibodies
• The presence of C4d and positive TG or anti HLA-2 has the worse renal graft survival
• The presence of dnDSA has worse renal graft survival
DSA as patient survival predictor
• Presence of anti-HLA antibody and patient survival has been studied
• Dunn et al- DSa positive patient had reduced actuarial survival at 5 years post transplantation
• Smith et al – dnDSA is independent predictor of poor patient survival
DSA monitoring and effect of C1q DSA on allograft survival
• C1q able to detect IgG antibodies and capable of fixing complement
• All C1q+DSA had AMR at next biopsy proved that it able to predict AMR
• C1q provides a further layer of Immunologic antibody information that may important to be an adjunct in optimising post-transplant care
• Abu et al- C1q+ DSA has 6 times more risk in losing the grafts than C1q-
• Chin et al-C1q+DSA after transplantation had AMR at the protocol biopsy proved that complement binding DSA able to predict AMR
• C1q+ DSA associated with greater incidence of acute allograft rejection and more likely to have C4d deposition in renal biopsy
Post transplantation monitoring
• Usually Develop DSA after 2 years of the transplantations
• 50% of AMR has been missed as it may take years to produce chronic vascular changes that leads to graft failure
• DSAA monitoring may help in early identification of patient with risk of rejection due to suboptimal IS due to non adherence
• DSA can be useful in adjustment of IS
• Early identification of DSA and sooner in starting anti-humoral therapy will improve overall survival rates
• Survival is better in those who had cleared DSA than those who had persistent DSA
Why Monitor DSA post transplantation
• 10 year renal allograft survival in early antibody developers (40% of kidney transplant receivers with AMR had TG
• Solid organ transplant recipient with TG had <50% 5 year graft survival
Luminex
• Detects low level DSA which may put patient at risk of rejection
• Highly sensitive in determination of a patient’s antibody profile
• Change in DSA or newly formed DSA may reveal an early rejection process
Reem Younis
3 years ago
The role of anti-HLA antibodies in transplantation:
-Preformed Anti-HLA antibodies were the result of pretransplant sensitization(blood transfusion, previous transplant, or pregnancy).
-Post-transplant Anti-HLA antibodies direct against donor-specific HLA class I and class II mismatches.
-Pre or post-transplant Antibodies increase the risk of rejections and poor patient and graft survival.
– Preformed DSA leads to acute AMR and lower graft survival.
-Large cohort studies showed 25% of transplant recipients have antibodies while previous renal transplant data have shown up to 96% of rejected allografts develop some level of detectable DSA.
-Anti-HLA antibodies contribute to the development of chronic renal failure that leads to renal allograft failure. Sub-clinical antibody-mediated rejection :
– De novo DSA may develop without an immediate impairment of graft function that leads to sub-clinical antibody-mediated rejection(SAMR) and graft deterioration and long-term graft dysfunction.
-SAMR is associated with microcirculation inflammation.
-It is due to non-adherence to immunosuppressive therapy.
-The range of de novo DSA post-transplant is 24% -62% with the highest presence in post-liver transplant recipients.
-De novo DSA in renal transplant, predominately directed at class II donor HLA mismatches and associated with poor outcomes. Effect of C1qDSA on allograft survival:
-Not all DSAs are complement-fixing
-C1q assay can detect IgG capable to fix and activate complement.
– Recipients with C1q(+)DSA have a high incidence of acute allograft rejection and are more likely to have C4d deposition found on biopsy. Post-transplantation monitoring of DSA:
-Many transplant recipients develop de novo DSA within 2 years of transplant. Advantages of DSA monitoring
1 .monitoring of DSA can facilitate early detection and diagnosis of chronic rejections.
2. Early identification of recipients at risk for rejection due to insufficient immunosuppression due to poor compliance with immunosuppressive therapy.
3. Can be useful in the adjustment of immunosuppressive therapy post-transplant.
4. Help in the precise adjustment of anti-humoral therapy and better outcomes.
-Luminex-based single-antigen beads allow for a precise, highly sensitive determination of the patient,s antibody profile and can detect a low level of DSA.
-The frequency of post-transplant monitoring will be patient-specific and serial monitoring more valuable than a single test.
– Kimball et al .preformed DSA against HLA class I and II decline by 90% at 6 months and undetectable at 1 year with effective treatment.
Hamdy Hegazy
3 years ago
DSAs are antibodies directed against antigens expressed on donor organs, they can develop in the transplant recipient pre or post transplantation, usually they attack the endothelium on the allograft resulting in AMR. They are associated with graft rejection, graft loss and lower patient survival.
At any given time, 25% of transplant recipients have DSAs. 96% or renal transplant recipients with rejected allografts develop some level of detectable DSA.
Early identification and removal of clinically harmful DSA associated with AMR, pre- and post transplant, may prevent allograft loss.
Pateints with preformed DSAs are at greater risk of acute AMR and lower graft survival.
Patients with preformed DSAs and de novo DSAs are at increased risk of chronic rejection.
Subclinical AMR typically is associated with non-adherence to immunosuppressive therapy and usually associated with preformed DSAs and negative C4d stain.
De novo DSAs have been associated with higher graft failure, they are more common in liver transplantation (62%), and less common with kidney-pancreas transplant patients.
De novo DSA development in renal transplant recipients, predominantly directed at class II donor HLA is associated with poor outcome and is detectable well before graft failure.
In liver transplant recipients, the presence of de novo DSA within the first year of liver transplantation was more common in recipients presented with chronic rejection, 92% of them had detectable DSAs before graft failure. DSA+/diffuse C4d +>>>higher frequency of acute cellular rejection and steroid resistant rejection. The role of DSA follow up in pancreas and multi-visceral transplantation is a valuable diagnostic tool in diagnosis and treatment of acute rejection.
DSA+ in lung transplant recipients is associated with higher prevalence of bronchiolitis obliterans and shorter graft survival. In cardiac transplantation it is associated with accelerated cardiac allograft vasculopathy and death.
Renal transplant recipients with C1q + DSA were nearly 6 times more likely to lose their grafts than those with C1q – DSA.
Benefits of monitoring DSA post renal transplantation: 1- Early identification for those at risk of rejection especially due to non-adherence to immunosuppressive drugs. 2- Adjustment of IS drugs post transplantation.
SAB Luminex allow for precise determination of the patient’s antibody profile. Makes discrimination between DSA and non-DSA possible. Can detect low level DSA which increases the risk of rejection. Detect changes in DSA or new DSA specificities which can reveal early rejection process.
How to Monitor DSA post transplantation:
DSA should be done in all RTx recipients at least one time in the first 3-12 months post transplant depending on their risk (low, standard, and high)
For subsequent determination:
if stable renal function in low risk patients, DSA testing by should be done at least every 1-2 years
if stable renal function in medium and high risk, DSA testing should be done annually.
DSA follow up periodicity can be modified if any of the following:
change in medications.
variability of CNI level.
poor adherence to IS medications.
graft dysfunction
Mahmud Islam
3 years ago
With the continuum of acute, late, and early chronic rejection contrary to previous thoughts of T cell role as the only important factor, It was proved that DSA’s either previously performed or Denovo formed to have a key role in transplant rejection. acute rejections may be of more favorable effect because of early detection as patients are monitored more frequently especially through first-year post-transplantation. later chronic rejection may be clinically evident after fibrotic changes that are irreversible. during follow-up, the gradual increase in creatinine level may be attributed and sometimes confused because of many factors that may be falsely considered as the cause (drugs dose, trough level, infections, dehydration, etc.)
With advanced technology and the revolution of single-antigen detection, we are now able to detect and intervene with rejections.
Routine testing in the first year in highly sensitized cases is essential.
Any unexpected change in eGFR should alert us.
Abdullah Raoof
3 years ago
DSA either preformed or denovo has imprtant in graft outcome .
25% of all kidney transplant has DSA , 60% graft rejection has DSA .
There is strong relationship between development of DSA and occurence of chronic graft failure .
DSA monitoring will help to diagnose subclinical AMR which has an impact on graft function outcome . subclinical AMR is closely related to drug non adherence .
development of denovo DSA is associated with higher incidence of graft failure .
negative effect of denovo DSA on graft may need years to appear .
in addition to rejection and graft loss ANTI HLA ab is demonstrated to be related with patient survival .
frequency of DSA monitoring is still not settled and it is depend on the patients degree of risk . the highest risk the more frequent monitoring is needed .
Weam Elnazer
3 years ago
post-transplant care has improved, although graft function is still suboptimal. For dead and live donor kidney transplants, the adjusted 10-year allograft survival rates are only 40.8 and 57.9%, respectively.
Antibody-mediated rejection (AMR) is a major cause of late-stage graft failure.
Prior to transplantation, anti-Human Leukocyte Antigen (HLA) antibodies were characterized as preexisting circulating antibodies present in the recipient’s immune system (blood transfusion, previous transplant, or pregnancy).
It has recently become popular in the transplant community to check for clinically relevant antibodies directed against donor-specific HLA class I and class II mismatches.
Antibodies directed against antigens produced on donor organs result in an immunological assault on the transplanted organ, increasing the likelihood of graft loss and/or rejection.
DSA affects the allograft endothelium, causing AMR. Allograft deterioration is caused by continuous changes in DSA development and clinical events that eventually limit graft function and survival.
Preformed DSA may result in immediate hyperacute rejection and graft necrosis, as well as early acute ABMR and graft necrosis.
The development of de novo DSA may result in late acute ABMR, chronic ABMR, and transplant glomerulopathy. A variety of DSA properties, including as HLA classes, specificity, strength, IgG subclasses, and complement binding ability, influence the clinical manifestations of ABMR.
Those in the low-risk category ( no DSA prior to transplant) should have their DSA checked at least once every 3 to 12 months for the first 3 to 12 months after transplant.
In the Intermediate risk category the DSA should be checked In the first month after transplantation, check the DSA.and if any one of the following( change in immunosuppression, graft dysfunction, non-adherence to the medication) .
In high risk category DSA should be conducted on a regular basis at 1, 3, 6, and 12 months following Tx, and then once a year afterwards.
Asmaa Khudhur
3 years ago
The Role of anti-HLA Antibodies in Transplantation
Anti-HLA ABs can be defined as the preformed circulating antibodies present in the recipient’s immune system which were the result of a sensitization event pre-transplant (blood transfusion, previous transplant, or pregnancy).
Whether detected pre- or post-transplant, the presence of antibodies directed against antigens expressed on donor organs, when not treated clinically, results in an immune attack on the transplanted organ, and increases risk of graft loss and/or rejection.
There is strong evidence that anti-HLA antibodies contribute to the development of chronic renal failure, the leading cause of renal allograft failure
The early identification and subsequent removal of clinically harmful DSA associated with AMR, both pre- and post-transplant, may prevent allograft loss.
offers highly sensitive and specific solid-phase assays allowing for the accurate identification of DSA both pre- and post- transplant.
Antibody-mediated rejection has 2 mode of occurrence:
Early and acute due to preformed ABs
Late and chronic due to denovo ABs(DSA)
DeNovo DSA also can lead to early acute rejection.
Patients with preformed DSA and those who develop de novo DSA are at an increased risk of having chronic rejection.
Sub-Clinical Antibody Mediated Rejection
SAMR is a frequent finding in patients with preformed DSA
SAMR reported to have an impact on long-term graft dysfunction and deterioration, instead of having an immediate impact
De Novo DSA in Post-Transplant Solid Organ Transplant Recipients
(dnDSA) post-transplantation has been as- sociated with higher graft failure rates.
the range of dnDSA:-
• 62% of liver transplant patients19
• 56% of lung transplant patients16
• 33% of heart transplant patients17
• 27% of multivisceral transplant patients18
• 24% of kidney-pancreas transplant patients
DSA is Predictive of Lower Graft Survival
the risk of developing chronic rejection leading to AMR increases with the presence of anti-HLA-Class II antibodies.
the presence of HLA antibodies predicts kidney graft loss.
In addition to rejection and graft loss, a significant association between the presence of anti-HLA antibody and patient survival has been demonstrated.
DSA Monitoring:
The C1q assay preferentially detects antibodies that have the capacity to fix and activate complement.
C1q (+) DSA were nearly 6 times more likely to lose their grafts than those with C1q (-) DSA.
C1q (+) DSA after transplant had AMR at the next biopsy, demonstrating that complement binding DSA is predictive of AMR.
The presence of C1q (+) DSA was associated with a significantly greater incidence of acute allograft rejection, and patients with C1q (+) DSA were significantly more likely to have C4d deposition found on biopsy.
Post-transplantation Monitoring:
Serial monitoring of the alloantibodies follow- ing transplantation may facilitate early diagnosis of chronic rejection.
DSA monitoring may be useful in the adjustment of immunosuppressive therapy post-transplant.
DSA monitoring may be useful in the adjustment of immunosuppressive therapy post-transplant. The close surveillance of humoral immunity is mandatory for the precise adjustment of anti-humoral therapy and optimal outcomes.
Why Monitor DSA Post-Transplant?
• Ten-year renal allograft survival in early antibody developers (<1 year) was 27% vs. 80% in the late antibody developers.
• More than 40% of kidney transplant recipients with AMR developed transplant glomerulopathy.
• Solid organ transplant recipients diagnosed with transplant glomerulopathy experienced 5-year graft
survival rates less than 50% from the time of diagnosis.
• 15-year graft survival in early antibody developers (<1 year) was 52% vs. 40% in late developers.
• De novo DSA production in heart transplant recipients was strongly associated with decreased patient
survival (HR = 3.198) and worse for those with persistent DSA (HR = 4.351).
• Many post-transplant solid organ transplant recipients developed de novo DSA secondary to
non-adherence to immunosuppressive therapy, particularly in the pediatric population.
• Insufficient immunosuppression may contribute to the development of de novo DSA and AMR
secondary to misclassifications based on C4d negativity
Why Monitor With Single-Antigen Beads?
Luminex®-based single-antigen beads (SAB) allow for a precise, highly sensitive determination of a patient’s antibody profile. This makes discrimination between donor-specific and non-donor-specific antibodies pos- sible.
The use of Luminex® SABs as part of a comprehensive monitoring program provides a number of advantages, including:
• The presence of low-level DSA can put patients at
risk for rejection
• Changes in DSA or the appearance of new DSA
specificities may reveal an early rejection process
Sensitivity of Antibody Detection Methods
Optimizing DSA Monitoring Strategies
Choosing a monitoring frequency based on a patient’s individual risk of developing AMR post-transplant will be the most efficient and clinically relevant strategy.
Huda Al-Taee
3 years ago
In your own words, summarise the role of anti-HLA Antibodies in Transplantation
Anti HLA antibodies are either pre-formed which is present in the patient serum as a result of sensitizing event pretransplant (blood transfusion, pregnancy, previous transplant) or formed de novo post transplantation. Whether detected pre or post transplantation, they are associated with increased risk of graft loss and/or rejection. DSA attack the endothelium resulting in ABMR. Preformed DSA can cause instant hyperacute rejection and graft necrosis, also they can cause early acute ABMR. De novo DSA can cause late acute ABMR, chronic ABMR & transplant glomerulopathy. The clinical phenotypes of ABMR are determined by the complex characteristics of DSAs including HLA classes, specificity, strength, IgG subclasses, and complement binding capacity. DSA may develop without causing an immediate impairment of graft function, this type of rejection is called subclinical rejection and is associated with long term graft dysfunction. DSA is also a predictive of lower patient survival.
How would you monitor DSA post-transplantation?
The patient immune risk should be stratified before deciding on DSA monitoring regimen, the risk classified as:
low risk: no anti HLA antibodies, no sensitizing events and first transplant
medium risk: anti HLA antibodies, cPRA <80%, previous sensitizing event, no DSA, no previous transplant, no DR, DQ mismatch, or acute rejection.
high risk: anti HLA antibodies > 80%, with pre traNsplant DSA.
Testing for DSA should be done in all kidney transplant recipients at least one time in the first 3-12 months post transplant.
For subsequent determination:
if the renal function is stable in low risk patients, screening by lumenix testing should be done at least every 12-24 months
in medium and high risk patients with stable renal function, screening should be done every 12 months.
The monitoring periodicity should be adjusted according to the patient’s clinical situation.
Proceeding to DSA level monitoring regardless of the risk level is required in the following conditions:
when significant change in medications is required
in cases of significant variability of CNI level
poor adherence to IS medications is suspected
graft dysfunction
Reference:
Crespo M.,Zárraga S., Alonso A., Beneyto I., et al. Monitoring of Donor-specific Anti-HLA Antibodies and Management of Immunosuppression in Kidney Transplant Recipients: An Evidence-based Expert Paper.
Transplantation. August 2020,Volume 104,Number 8S2.
1. In your own words, summarise the role of anti-HLA Antibodies in Transplantation.
Anti-HLA antibodies are those antibodies which are formed in a transplant recipient due to exposure to a sensitization event like prior transplant, blood transfusion or pregnancy. Antibodies can develop post-transplant (de-novo) due to HLA mismatch, under-immunosuppression, as well as acute insults like acute T cell mediated rejections, infections etc.
These antibodies act at the vascular endothelium of the renal graft, leading to antibody mediated rejection, which would cause chronic damage in the graft ultimately reducing graft function and survival. It has been shown that upto 96% of patients with graft rejection develop DSAs. Early and acute AMR is usually seen with pre-formed DSAs while late chronic AMR is seen with de-novo DSAs. AMR in graft with de-novo DSA have poorer prognosis than in patients with pre-formed DSAs. DSAs are also associated with subclinical AMR, which is usually seen in patients having under-immunosuppression due to non-adherence.
If de-novo antibody develop after first year of transplant, the 15 year graft survival falls to 40% as compared to 52% in patients who develop de-novo DSA within 1 year of transplant. de-novo DSA, especially against class II HLA are associated with poor graft and patient prognosis. DSA is associated with severe forms of rejections.
DSA monitoring post-transplant is important to diagnose subclinical AMR as well as clinical AMR and to tailor immunosuppression according to patient-donor characteristics (for example decision regarding augmenting or reducing immunosuppression in presence of side-effects).
DSA monitoring involves single antigen bead assay as well as C1 q assay which is more specific for complement fixing and activating antibodies. Early detection of DSA and treatment to reduce them leads to better graft survival.
2. How would you monitor DSA post-transplantation?
Post transplant DSA monitoring is an important step in transplant management.
Guidelines (1) recommend:
In low risk group (first transplant, no desensitization, no DSA pre transplant): Check DSA at least once in first 3 to 12 months post transplant.
In Intermediate risk group (DSA negative, but prior history of DSA presence): Check DSA in first month post transplant
If DSA is negative, no further testing is required in these 2 groups unless there is change in immunosuppression, graft dysfunction, non-adherence or if the patient is transferred to remote unit.
If DSA is positive, kidney biopsy is done and if it shows AMR, it should be treated.
In high risk group (DSA positive) and very high risk group (desensitized cross match positive), DSA testing with kidney biopsy should be done during first 3 months. If biopsy shows AMR, treatment should be initiated. If biopsy is negative, but DSA rising, then it should be treated as AMR. If no AMR in biopsy, monitor DSA.
After one year post transplant, routine DSA monitoring is not recommended except if there is change in immunosuppression, graft dysfunction, non-adherence or if the patient is transferred to remote unit.
But a recent paper (Crespo et al, Transplantation 2020) recommends DSA monitoring in low risk group at least once in 12 to 24 months and in other groups annually.
References:
1) Tait BD, Susal C, Gebel HM, et al. Consensus Guidelines on the Testing and Clinical Management Issues Associated With HLA and Non-HLA Antibodies in Transplantation. Transplantation 2013;95:19-47.
2) Crespo M, Zarraga S, Alonso A, et al. Monitoring of Donor-specific Anti-HLA Antibodies and Management of Immunosuppression in Kidney Transplant Recipients: An Evidence-based Expert Paper. Transplantation 2020;104:S1-S12.
This statement is based on work by Lee et al, published in 2009.
Lee PC, Zhu L, Terasaki PI, et al. HLA-specific antibodies developed in the first year posttransplant are predictive of chronic rejection and renal graft loss. Transplantation 2009;88:568–574.
Shereen Yousef
3 years ago
Summary of the role of anti-HLA Antibodies in Transplantation.
Presence of DSA either preformed or de novo Is well known risk initiate an immune response against graft endothelial cells and results in AMR .
solid-phase assays allowing for the accurate identification of DSA both pre- and post- transplant.
There is a strong evidence that anti-HLA Ab results in renal allograft failure.The early detection and removal of DSA associated with AMR, both pre- and post-transplant, may prevent allograft loss.
Types of AMR;
Antibody mediated rejection can present as an early acute process due to preformed DSA or de novoDSA, or late and may be chronic rejection
usually due to de novo antibody production.
preformed DSA is a significante risk of acute AMR which will lead to lower graft survival.
Chronic rejection is a major cause of graft loss occurs due to repeated cycles of AMR and repair result in distinct changes in the microvasculature of the allograft.
Patients with preformed DSA and those who develop de novo DSA are at an increased risk of having chronic rejection.
Sub-clinical antibody mediated rejection occurs when DSA either preformed or de novo without immediate affection of graft function but causes long term graft dysfunction.
non-adherence to IS therapy is a common cause of SAMR.
Renal biopsy after one year showed microcirculatory inflammation denoting presence of de novo DSA and C4d stain msy be negative for SAMR.
ROLE OF DSA IN SOLID ORGAN TRANSPLANTATION
De novo DSA is associated with high risk of graft failure of different solid oragans with highest level in liver transplants 62% and lowest in renal graft 24%.
DSA against HLA antigens specially class II is associated with higher incidence of AMR ,SAMR and chronic rejection with poor outcome on both patients and graft survival.
MFI value also affect the graft survival where MFI > 3000 had poor graf survival and 6000 MFI had the highest risk of graft loss by AMR.
Presence of DSA may predict rejections and graft failure in different solid oragans transplant as in liver and pancreas transplant , detection of DSA in serum is more valuable than doing biopsy in diagnosing AMR and steroid resistant liver rejection.
C1q assay detects IgG antibodies that can fix and activat the classical complement pathway with exclusion of non-complement fixing antibodies which may be clinically irrelevant to organ rejection.
C1q+ DSA is associated with significant higher incidence( up to 6 fold ) of acute rejection and more C4d deposition.
Post-transplant DSA monitoring:
It is important to allow early diagnosis of chronic rejection, antibodies may take months to years to produce the chronic vascular changes leading to graft failure, early treatment remove DSA will improve the outcome.
Also identify non adherent patients at risk of rejection.
Proper adjustment of anti-humoral immunosuppressive therapy post-transplant.
HOW TO DETECT DSA
Luminex based single antigen beads determine the patient’s antibody profile, and allow differentiation between donor and non-donor specific antibodies, determine the presence of low level DSA which can increase risk of rejection and detect changes in DSA that may reveal an early rejection process.
Timing for assays must be tailored according to each patient risk
Serial monitoring of DSA is more valuable than single point testing, particularly in the post-transplant setting, and is crucial in optimizing patient outcomes
Kimball et al. performed quarterly monitoring of patients for 3 years post-transplant and reported that 65% of patients eliminated antibody within the first year of transplant due to early detection and subsequent treatment. In those patients that exhibited pre-transplant DSA against Class I and II HLA, antibody levels declined by 90% at 6 months and were undetectable at 1 year with effective treatment.
DSA against HLA class I and class II mismatches has been a significant . Whether detected pre- or post-transplant, the presence of antibodies directed against antigens expressed on donor organs, when not treated clinically, lead to increases risk of graft loss and/or rejection.
Sub-clinical antibody mediated rejection: DSA may also lead AMR without affecting the kidney function leading to decrease graft survival .
De Novo DSA in Post-Transplant: De novo donor-specific HLA antibodies (dnDSA) post-transplantation has been associated with higher graft failure . The range of dnDSA is 24% to 62% with the highest presence in post liver transplant recipients .In liver transplantation The presence of de novo DSA within the first year of liver transplants was more common in patients that presented with a chronic rejection; 92% had detectable DSA before chronic-rejection-induced graft failure occurred . DSA can be used to detect rejection early in pancreas, multi-visceral , small bowel transplants and in lung transplant where Anti-HLA antibodies are associated with a higher prevalence of Bronchiolitis Obliterans Syndrome which end with short graft survival Antibodies in heart transplant may activate complement and accelerate Cardiac allograft vasculopathy which is the primary cause of death and re-transplant in long-term . How would you monitor DSA post-transplantation? DSA should be monitor at 1,3,6 and 12 months after transplantation , then once per year. Patients a significant increase in DSA titer, allograft biopsy may be indicated . Protocol biopsies to detect subclinical rejection .
Expand your answer, you have missed various important information that shall compliment the report.
Hinda Hassan
3 years ago
In your own words, summarise the role of anti-HLA Antibodies in Transplantation.
Antibodies were found in 25% at any given time in a cohort of transplant recipient. DSA are present in 96% of rejected grafts. These can develop pre-transplant (preformed) or they can develop de novo after transplant at any point of time. de novo DSA are due to noncompliance or insufficient immunosuppressant drugs
Detection of antibodies whether preformed or de novo and determining whether they are DSA is valuable for choosing induction, desensitization, immunosuppressants or changing dosed.
Both types can result in early graft dysfunction , acute ,subclinical or chronic AMR, which can end with graft loss and reduced 5 year patient survival (the later with DSA)
DSA are associated with subclinical rejection and transplant glomeulopathy and hence with reduced graft survival .
DSA presence, persistent, type ( esp class II DSA ) and high titer can predict graft loss and risk chronic rejection.
De novo DSA can end with graft failure (range from 62% in liver transplant up to 24% in kidney-pancreas transplant.
in liver transplant and in pancreas transplant , detection of DSA in serum is more valuable than doing biopsy in diagnosing AMR and steroid resistant liver rejection
DSA can be used to detect rejection early in pancreas, multi-visceral , small bowel transplants and in lung transplant where Anti-HLA antibodies are associated with a higher prevalence of Bronchiolitis Obliterans Syndrome which end with short graft survival
Antibodies in heart transplant may activate complement and accelerate Cardiac allograft vasculopathy which is the primary cause of death and re-transplant in long-term
How would you monitor DSA post-transplantation?
Through Luminex based single antigen beads (SAB) to detect low titer and determine the type of antibodies.
The frequency of testing is better to be patient specific and to be done periodically. The utmost benefit will be within the first year post transplantion especially for sensitized patients.
C1q assay detect complement fixing DSA which can predict AMR in heart and renal transplant as proved by studies
Early detection of DSA provide a tool to pick AMR at an early stage which would provide a chance for rescuing the graft
According to TTS the frequency of monitoring should be based according to the degree of risk low risk individuals are screened once from 3-12 months post transplant . Intermediate risk need screen in the first month . At any point,once DSA are detected ,a biopsy need to be taken to look for AMR. High risk and very high risk need a biopsy in the first month.
Heba Wagdy
3 years ago
Role of anti-HLA antibodies in transplant: Anti-HLA antibodies are preformed circulating antibodies in recipients due to sensitization (blood transfusion, pregnancy or previous transplant), detected pre or post-transplant, directed against antigens expressed on donor organs, attack the endothelium causing AMR. Progression of DSA development, if not clinically treated, leads to chronic changes which decrease graft function and survival. Sub-clinical antibody mediated rejection: Type of rejection where DSA develop without immediate affection of graft function but cause long term graft dysfunction. Common in patients with preformed DSA, and who are non-adherent to immunosuppressive therapy. Allograft biopsy one year post transplant mostly show microcirculatory inflammation denoting presence of de novo DSA De novo DSA post-transplant: The negative outcome of de novo DSA may appear several years after production of the antibodies. Studies showed that de novo DSA against class II HLA mismatches have worse outcome, associated with higher risk of chronic rejection and AMR DSA is predictive of lower graft survival: HLA antibodies are predictive of graft loss. Studies showed that presence of anti-HLA antibodies is associated with poor patient survival. Effect of C1q DSA on allograft survival: Novel C1q assay detects IgG antibodies capable of fixing and activating the classical complement pathway with exclusion of non-complement fixing antibodies which may be clinically irrelevant to organ rejection. It is used with other methods to define patient’s immunological profile. C1q+ DSA is associated with significant higher incidence of acute rejection and more C4d deposition on biopsy. Post-transplant DSA monitoring: • Serial monitoring of DSA post-transplant allow early diagnosis of chronic rejection, this is important as antibodies may take months to years to produce the chronic vascular changes leading to graft failure, early initiation of anti-humoral therapy can remove DSA and improve the outcome. • Early identify patients at risk of rejection due to insufficient immunosuppression due to non-adherence • Allow adjustment of anti-humoral immunosuppressive therapy post-transplant. Luminex based single antigen beads determine the patient’s antibody profile, and allow differentiation between donor and non-donor specific antibodies, determine the presence of low level DSA which can increase risk of rejection and detect changes in DSA that may reveal an early rejection process.
1. In your own words, summarise the role of anti-HLA Antibodies in Transplantation.
The presence of anti-HLA antibodies whether preexisting or newly formed affects graft survival.
There are some criteria that are associated with poor graft survival:
1- DSA titer:
In the study by Lefaucheur et al (2010), DSA titer> 6000 MFI had the highest risk (100 fold) of graft loss by AMR. Also, graft survival was lower when MFI > 3000 in the same study. 2- DSA time of origin: De novo DSA may confer a poorer graft outcome when compared with preexisting DSA. Yjis was illustrated by several studies. One of them was the study by Wiebe et al (2012), the median 10-year graft survival for those with de novo DSA was lower than the No de novo DSA group (57% vs. 96%, p<0.0001). 3- DSA class: In a study by Lefaucheur et al (2016), IgG4 was associated with a delayed allograft loss, while IgG3 conferred a faster graft loss. 4- DSA responsiveness: Many trials were in concordance that DSA response to immunosuppressive medication was associated with more favorable allograft survival. 5- C1q binding ability: Although some studies revealed that DSA antibody ability to bind with complement was associated with poorer outcomes (Loupy et al, 2013), some authors contradict this finding proposing that complement binding is related only to antibodies strengths (Yell et al, 2015).
1. How would you monitor DSA post-transplantation?
DSA should be routinely performed at 1,3,6 and 12 months after Tx, then once per year. For those patients who show a significant increase in DSA titer, allograft biopsy may be warranted. (Tait BD et al, 2013)
Roles of anti-HLA antibodies in kidney transplantation
The presence of antibodies directed against donor antigens ,whether pre or post kidney transplant results in an immune attack on the endothelium of the allograft, resulting in subsequent AMR . Sub clinical-AMR is also a frequent finding in patients with preformed DSA . There is strong evidence that anti-HLA antibodies contribute to the development of graft nephropathy, the leading cause of renal allograft failure . Survival was significantly worse in recipients who had persistent DSA than in those who had cleared the DSA. Death-censored allograft survival stratified by percent reduction in immune dominant DSA at 14 days post-biopsy Renal allograft survival stratified on ability to yield antibody reduction . The development of de novo donor-specific HLA antibodies (dnDSA) post-transplantation has been associated with higher graft failure rates. May cause sub-clinical AMR that is associated with long term graft dysfunction .The range of dnDSA is 24% to 62% with the highest presence in post liver transplant recipients. Several prospective and retrospective studies have demonstrated that de novo DSA development in renal transplant patients, predominately directed at Class II donor HLA mismatches, is associated with poor outcomes, and is often detectable well before graft failure.
DSA monitoring ;
The routine monitoring of DSA may provide early identification of those patients at risk for rejection due to insufficient immune suppression as a result of poor compliance with immunosuppressive therapy. DSA monitoring may be useful in the adjustment of immunosuppressive therapy post-transplant . Studies have shown that when DSA is identified early through routine monitoring, the initiation of anti-humoral therapy may begin sooner, allowing for DSA to clear and improving overall survival rates. Research has suggested that the evaluation of the C1q assay provides a further layer of immunologic antibody information that may prove to be an adjunct in optimizing post-transplant care. In a study reported by Yabu et al., kidney transplant recipients with C1q (+) DSA were nearly 6 times more likely to lose their grafts than those with C1q (-) DSA.
Optimize DSA monitoring strategies
Choosing a monitoring frequency based on a patient’s individual risk of developing AMR post-transplant will be the most efficient and clinically relevant strategy. Serial monitoring of DSA is more valuable than single point testing, particularly in the post-transplant setting, and is crucial in optimizing patient outcomes. In those patients that exhibited pre-transplant DSA against Class I and II HLA, antibody levels declined by 90% at 6 months and were undetectable at 1 year with effective treatment.
The Role of anti-HLA Antibodies in Transplantation
The Spectrum of Antibody Mediated Rejection
Early or late antibody mediated rejection is associated with deleterious renal outcomes. The presence of preformed or de Novo anti-HLA DSAs carry high risk of humoral rejection.
Preformed antibodies are implicated in the development of early acute rejection while de novo DSA can develop in the early and late post-transplant period, resulting in disastrous inflammatory response and graft failure.
Patients with preformed DSA and those who develop de novo DSA are at an increased risk not only for acute rejection but also chronic rejection based on the histopathological Banff criteria.
Sub-Clinical Antibody Mediated Rejection
The development of biopsy proven signs of rejection in the presence of DSA defines subclinical AMR. Subacute rejection has been reported to have an impact on long-term graft dysfunction.
Subacute rejection is a common finding in patients with preformed DSA, even with negative C4d. The detection of De novo antibody could be histologically reflected by subclinical AMR, which is associated with long- term negative outcomes typically occurring several years after de novo antibody production.
The majority of de novo DSA are directed against Class II donor HLA in particular with HLA class II mismatches.
DSA is Predictive of Lower Patient Survival
In terms of survival outcomes, survival was significantly decreased at 5-years post-transplant in DSA positive patients compared to DSA negative patients.
The Future of DSA Monitoring: Effect of C1q DSA on Allograft Survival
C1q assay is used to detect IgG antibodies capable of fixing complement and developing cell lysis.
In one study, kidney transplant recipients with C1q (+) DSA were nearly 6 times more likely to lose their grafts than those with C1q (-) DSA. The presence of C1q (+) DSA was associated with a significantly greater incidence of acute allograft rejection, and patients with C1q (+) DSA were significantly more likely to have C4d deposition found on biopsy. The C1q assay preferentially detects antibodies that have the capacity to fix and activate complement.
Post-transplantation Monitoring
Serial monitoring of DSA in sensitized, mismatched recipients or in centers with protocol biopsies and finally in patients with deterioration of kidney function, is essential for early detection of alloantibodies following transplantation. Early diagnosis of acute or chronic rejection with appropriate management is associated with better outcomes. In patients at risk for rejection, DSA monitoring may be helpful in the adjustment of immunosuppressive therapy post-transplant.
Why Monitor DSA Post-Transplant?
-Ten-year renal allograft survival is poor in early antibody developers .
-High risk of transplant glomerulopathy in recipients with AMR.
-Survival rates in recipients diagnosed with transplant glomerulopathy is less than 50% from the time of diagnosis.
-Graft survival in early antibody developers is better than late developers.
-De novo DSA formation is strongly linked with non-adherence to immunosuppressive therapy.
Why Monitor With Single-Antigen Beads?
Luminex-based single-antigen beads remains the better diagnostic test to detect with high specificity anti-HLA DSA allowing for high sensitive determination of a patient’s antibody profile.
In spite significant improvement in post-transplant care, long term graft function is less than optimal.
Antibody mediated rejection (AMR) due to late stage graft failure is a main cause of poor graft survival .
The presence of antibodies directed against donor antigens results in an immune response on the transplanted organ, and increases risk of graft rejection if not treated.
Anti-HLA antibodies contribute to the development of renal allograft failure. The early identification and removal of DSA occurring with AMR, both pre- and post-transplant, can prevent allograft loss.
Highly sensitive and specific solid-phase assays enable detection of DSA both pre- and post- transplantation
Antibody mediated rejection can occur early by preformed DSA while late and chronic rejection can occur by denovo DSA.
subclinical antibody mediated rejection SAMR caused by DSA affects long-term graft function negatively.
For SAMR some cases are negative for C4d stain caused by non-adherence to immunosuppressive therapy leading to microcirculation inflammation on renal biopsies 1 year post transplantation.
The detection of denovo DSA was associated with high rate of graft failure, the biggest percentage was identified in liver transplant recipients.
Studies have concluded that HLA antibodies can predict renal graft loss.
In liver transplantation the differentiation between AMR and cholethiasis is difficult clinically and pathologicaly.
The diagnosis of AMR in liver transplant recipients can be by the presence of DSA in the recipient serum.
Bile duct injury in Cd4 livetransplant recipents is associated with DSA
In pancreatic transplantation the presence of pretransplant and posttransplant DSA indicates poor graft outcome
DSA monitoring in pancreas, multi-visceral and small bowel transplants is an important diagnostic tool in early diagnosis and treatment of acute rejection.
Anti-HLA antibodies are accompanied by the occurrence of Bronchiolitis Obliterans Syndrome , it can predicts its occurrence nearly 1 year before its occurrence.
Circulating antibodies can lead to cardiac allograft vasculopathy leading to graft loss in cardiac transplantation.
Monitoring of the DSA post transplantation may enhance early diagnosis of chronic rejection specialy due to inadequate immunosuppresion. How to monitor DSA
-By using Luminex SAB to detect low levels of DSA and newly developed DSA which affects directly graft survival and management.
-C1q DSA complent fixing antibody specifically need to be identified as not all non complement fixing DSA are associated with graft loss ,suggesting that C1qDSA monitoring is crucial in predicting AMR.
A study demenostrtated that patients with C1q (+) DSA were more prone to have C4d deposition on biopsy.
Donor-specific antibodies (DSAs) can be classified according to the time of detection into a preformed DSA detected in the patient serum before transplantation and de novo DSA, which will be detected post-transplantation as a result of sensitization.
Risk factors for developing preformed DSA
Pregnancy
Blood transfusion
Previous transplant
Risk factors for developing denovo DSA
The most important factor is HLA mismatch especially class II mismatch
Presence of preformed DSA before transplantation
Younger age, Non living related (deceased) donor kidney
Planned subtherapeutic immunosuppression (due to malignancy, infection) or conversion to CNI free or CS free protocols or non compliance on immunosuppressive medication ( very significant risk factor)
Inflammation induced by infections, surgery or TCMR
The Role of anti-HLA Antibodies in Transplantation
DSA either preformed or formed after transplantation attacks the endothelium of the graft leading to :
· Acute ABMR
· Chronic ABMR
· Subclinical rejection
· All cause subsequent reduction of graft and patient survival
Although, preformed DSA is associated marked increase in the Incidence of occurrence of early ABMR and reduced graft survival, De-novo DSA associated AMR has poorer graft survival as compared to pre-existing DSA associated AM
Monitoring of DSA
Why
1- Diagnostic : since subclinical and clinical ABMR can occur either due to Planned subtherapeutic immunosuppression (due to malignancy, infection) or conversion to CNI free or CS free protocols or noncompliance on immunosuppressive medication
2- Therapeutic: immunosuppressive medications can be tailored according to DSA level
3- Prognostic : presence of DSA in the early post-transplant period is associated reduced graft survival when compared to DSA developed later on after 1 year (10 years graft survival 27% vs 80%, respectively), > 40 % of patients with ABMR develop transplant glomerulopathy which reduce significantly graft survival (5 years graft survival in patient with TG is < 50%)
How
Using single antigen bead assay as it is very sensitive and specific
C1q assay is a new assay that is capable of detecting only complement fixing IgG DSA , maybe used to predict graft survival since complement fixing DSA are associated with poor graft survival
When
DSA should be monitored once in early post-transplant period (first 3 month) in all patients
After first 3 month no further testing is required except in the following situations
⦁ Patients who has received desensitization to render cross match negative (only for first 1 year post transplant)
⦁ Modification of immunosuppression
⦁ Suspicion of non-adherence
⦁ Graft dysfunction
⦁ Transfer of the patient to another center
Some recommend assessment of DSA annually,
Some recommend measurement of DSA / 3months for first 3 years
What to do after detection of DSA
All patients with detectable DSA should undergo renal biopsy
Treatment is indicated in the following situations
1- Presence of DSA together with histologic features of ABMR
2- Rapid increase of DSA with normal or near normal biopsy in in patients who received desensitization to render cross match negative
Thank you for putting your summary in the form of questions (excellent)
In your indications you stated graft dysfunction you know quite well that by the time this happens the immune damage has long been taking place.
graft survival from either deceased or living donor is still not optimal in spite of good patient and graft care with advancement of immunosuppressive medications, chronic AMR is the major cause for graft loss.
Detection of DSA either early or post transplant is very important to guard against development of AMR which results from endothelial injury caused by attacking DSA, so its removal is the key to prevent AMR and improve graft survival.
Solid phase assay can be used for detection of DSA by SAB (single antigen bead).
Preformed DSA can induce immediate AMR or may not lead to graft dysfunction immediately and may induce its effect late and predispose to chronic AMR due to previous subclinical AMR.
Subclinical AMR (either c4d positive or negative) may be related to preformed DSA or de novo DSA caused by non-adherence or dose reduction of ISD.
De novo DSA developed post-transplant affects graft survival especially liver graft, and cardiac graft. In renal graft, it is developed and directed to class II HLA antigen, and is associated with negative impact on graft and patient survival.
In liver transplant, diagnosis of AMR is based on the presence of DSA in the patient serum, and is associated with negative outcome.
In the pancreas transplantation, diagnosis of AMR is complexed and not easy, so depending on the presence of DSA is crucial in the diagnosis of AMR which also associated with negative outcome.
Not all DSA are injurious to the graft with the same degree, so, determine the type is important.
Complement fixing is determined by C1q assay and c4d stain.
C1q DSA (c4d positive stain) is associated with acute AMR and negative impact on graft survival than negative C1q DSA.
Yearly monitoring of DSA is beneficial to detect any abnormality or early rejection attack hence augment ISD or adjust doses, this monitoring can be done by luminex SAB due to high sensitivity of it.
Very good for highlighting the time lapse between there detection and immune injury
Also the type of DSA. Class1or class2
Assafi Mohammed
3 years ago
The role of anti-HLA Antibodies in Transplantation:
DSA attacks the endothelium of the allograft, resulting in subsequent AMR.The progression of DSA development and the correspond- ing clinical events compound to damage the allograft, resulting in chronic changes over time that ultimately compromise graft function and survival.
De novo DSA can also develop in the early post-transplant period, resulting in acute rejection. Patients with preformed DSA are at significantly greater risk of having an acute AMR and have significantly lower graft survival.
Patients with preformed DSA and those who develop de novo DSA are at an increased risk of having chronic rejection.
DSA may also develop without an immediate impairment of graft function. This type of rejection, or sub- clinical antibody mediated rejection (SAMR), has been reported to have an impact on long-term graft dysfunction and deterioration, instead of having an immediate impact.
SAMR is also a frequent finding in patients with preformed DSA, some of which the C4d stain is negative for SAMR.
de novo DSA development in renal transplant patients, predominately directed at Class II donor HLA mismatches, is associated with poor out- comes, and is often detectable well before graft failure.
Several studies have demonstrated that the presence of HLA antibodies predicts kidney graft loss.
A recent study by Dunn et al. found that actuarial survival was significantly decreased at 5-years post-transplant in DSA positive patients compared to DSA negative patients (p=0.0006, HR = 10.0).
Monitoring of DSA post-transplantation:
The routine monitoring of DSA may provide early identification of those patients at risk for rejection due to insufficient immunosuppression as a result of poor compliance with immunosuppressive therapy.
Tests for monitoring DSA post transplantation in sequences of sensitivity are : CDC,CDC-AHG,ELISA,FLOWCYTOMETRY,LUMINEX-SAB
Luminex®-based single-antigen beads (SAB) allow for a precise, highly sensitive determination of a patient’s antibody profile. This makes discrimination between donor-specific and non-donor-specific antibodies possible.
Serial monitoring of DSA is more valuable than single- point testing, particularly in the post-transplant set- ting, and is crucial in optimizing patient outcomes.
Better work this time as you are using your own words a bit more.
Summering should be: Read, understand, and summarize in your own words.
Ibrahim Omar
3 years ago
1- In your own words, summarise the role of anti-HLA Antibodies in Transplantation.
Anti-HLA anti-bodies are included and constituting the main part of donor specific anti-bodeis (DSA).
DSA can be found as pre-transplant and can also be formed as De novo after transplant. the later can also develop early or late post-transplant.
De nov DSA increase the incidence of Anti-body mediated rejection (AMR) and will decrease the 5 year graft survival and also patient survival. DSA of anti-HLA- class II, have the poorer outcome.
Routine monitoring of De novo DSA has been thoroughly considered for early detection of AMR and so effective treatment can be done to improve the long-term graft survival. it can also detect poor compliance to immunosuppressive medications as a possible cause of De novo DSA. however, the frequency of monitoring is still variable and depends on patient risk factors for developing DSA.
DSA detection by C1q based assay is being used for DSA monitoring. it can detect IgG anti-bodies that is directly related to graft survival. it is estimated that patients with C1q +ve DSA are 6 times more to lose their grafts, if compared to those with C1q -ve DSA.
Luminex based single antigen beads are more highly sensitive and specific for De novo DSA detection. they are commonly used for DSA monitoring.
2- How would you monitor DSA post-transplantation?
the best test to be used is Luminex-based SAB.
the frequency is variable. Kimball et al., suggested quaterly DSA monitoring for 3 years. it was successful as 65 % of +ve patients eliminated these anti-bodies with effective ttt.
How would you monitor DSA post-transplantation? Post transplantation (months 0 – 12) a. Very high risk patients (desensitized):
Monitor DSA and conduct protocol biopsies in the first 3 months after transplantation.
1. If there is evidence of clinical or subclinical AMR, the patient should be treated.
2. If there is a rapidly increasing level of DSA accompanied by a biopsy showing no rejection, initiation of therapy to reduce the DSA levels should be considered.
b. High-risk patients (DSA positive/XM negative):
Monitor DSA and conduct a protocol biopsy in the first 3 months after transplantation.
1. If biopsy is positive for AMR, the objective is to treat.
2. If there is a rapidly increasing level of DSA accompanied by a biopsy showing no rejection, initiation of therapy to reduce the DSA levels should be considered.
3. DSA persists in the absence of biopsy proven rejection, immunosuppression should not be reduced, and additional monitoring should be considered.
4. If the DSA and biopsy are negative, follow as if low risk unless there is an inflammatory event,
in which case additional monitoring for DSA is recommended.
c. Intermediate-risk patients: Includes history of sensitization to donor antigen(s) by CDC and SPI but currently negative and history of sensitization with at least one positive test for HLA antibodies. Monitor for DSA within the first month.
1. If a DSA present, then perform a biopsy.
2. If biopsy is positive for rejection, the objective is to treat.
3. In the absence of biopsy-proven rejection, additional DSA monitoring should be considered within the first year.
4. Patients with a DSA in the absence of biopsy-proven rejection should not be considered for reduction in immunosuppression.
5. In the absence of a DSA follow-up as if low risk .
d. Low-risk patients (nonsensitized, first transplantation)
1. Screen for DSA under the following circumstances:
a) at least once in 3 to 12 months after transplantation.
b) whenever significant change in maintenance immunosuppression is considered (e.g., minimization/withdrawal/conversion).
c) suspected nonadherence.
d) graft dysfunction.
e) before transfer of care to a remote center outside the transplant center.
2. If DSA present, then perform a biopsy.
3. If the biopsy is positive for rejection the objective is to treat.
4. In the absence of biopsy-proven rejection ,additional DSA, monitoring should be considered within the first year.
5. Patients with a DSA in the absence of biopsy-proven rejection should not be considered for reduction in immunosuppression.
6. If no DSA present, then no additional testing in the first year is recommended in the absence of circumstances listed under point 1 above.
Post transplantation (month 12 onward) applies to all risk categories
a. Store at least one serum sample per year (i.e., on the transplantation anniversary).
b. Evaluate DSA in a current serum if any of the following conditions occur:
1. Significant change in maintenance immunosuppression is considered (e.g., minimization/withdrawal/ conversion).
2. Suspected nonadherence.
3. Graft dysfunction.
4. Before transfer of care to a remote center outside the transplant center.
c. If de novo DSA present or if there is an increase in previous DSA levels, perform a biopsy.
1. If biopsy is positive for AMR, the objective is to treat.
2. If biopsy is negative (no sign of rejection) monitor the DSA and monitor for a change in graft function.
3. Patients with a DSA even without biopsy proven rejection should not be considered for reduction in immunosuppression.
In your own words, summarise the role of anti-HLA Antibodies in Transplantation.
HLA antibody play a central role in graft survival.
There is a correlation between HLA antibodies and graft rejection.
Pre transplant immunosuppression needs to be tailored according to the DSA MFI levels.
Persistence of DSA at 1 year is associated with decreased gfr and chronic abmr.
Role of anti-HLA
Preformed DSA are detected before Tx and de novo DSA are detected post Tx due to sensitization in conditions like pregnancy, blood transfusion or previous Tx. Risk factors of de novo DSA formation:
HLA mismatch (especially class II);the most important.
.Young age ,deceased donor kidney
.Preformed DSA
.Subtherapeutic IS dose due to infection, malignancy or conversion to less potent IS.
.Inflammation due to surgery, infection or TCMR.
DSA with its different types injure endothelium and can lead to acute ABMR, chronic ABMR ,subclinical rejection and reduction pf patient and graft survival. De novo DSA have poorer outcome than preformed DSA.
Monitoring of DSA is either diagnostic eg in case of subclinical & clinical ABMR ,therapeutic to tailor IS protocols ,or for prognostication.
Method
usually using SBA for its sensitivity and specificity.
C1q is used for detecting complement fixing DSA.
DSA assay usually done once in the first 3 months following transplantation and later if indicated eg desensitized patients ,non adherence ,need for IS escalation ,graft dysfunction or transfer to another center. Some protocol implement DSA regular annually or 3 monthly for first 3 years. monitoring
Renal biopsy is indicated once DSA are detected
Treatment is started with detected DSA and BPABMR or in case of rapidly increasing DSA in desensitized patients with normal or near biopsy findings.
Donor specific antibodies are two types
when not treated clinically , it results in immune attack of the transplant organ ,it attacks the endothelial of graft resulting in subsequent antibody mediated rejection and graft loss
Antibody mediated rejection can be acute due to preformed antibodies or Denovo DSA that develop in the early post transplant period and can be late chronic process due to development of Denovo DSA antibodies later
sub clinical antibody mediated rejection where preformed HLA antibodies and Denovo DSA take months to years to produce chronic vascular changes and graft loss
presence of HLA antibodies kidney graft loss
Denovo DSA is an independent predictor of poor patient survival
Monitoring of DSA post transplant
Luminex based single antigen beads allow for highly sensitive determination of a patient antibody profile and discrimination between donor specific and non specific antibodies serial monitoring of DSA is more valuable than single point testing especially in post transplant period , choosing monitoring frequency based on patient individual risk of developing AMR
early detection and treatment improve the outcomes
The primary cause of poor graft survival is late stage graft failure secondary to AMR.
Performed circulating antibodies in recipients result in pre-transplant sensitisation.
Post-transplant development of clinically antibodies directed against donor specific HLA class I and class II mismatches which increase risk of graft loss or rejection.
DSA attacks endothelium of graft results in AMR and progression of development of DSA leads to chronic changes which reflected on graft function and survival.
Up to 96% of rejected allografts develop some level of detectable DSA .
There is association between anti-HLA antibodies and development of chronic renal failure which leads to renal allograft failure.
Early detection and removal of DSA pre-and post- transplant may prevent allograft loss.
Solid-phase assay helps in detection of DSA pre-and post-transplant.
AMR presents early and late after transplantation.
Sub-clinical antibody mediated rejection due to DSA which develops without immediate impairment of graft function.
High graft failure rates associated with denovo DSA post liver transplant recipients 62% and in post-kidney transplant recipients reaches 24%.
Patients with performed DSA and those who develop de novo DSA increase risk of having chronic rejection.
High frequency of denovo DSA or patients with non-adherence to immunosuppressive therapy. represented by micro circulation inflammation in late kidney biopsy.
SAMR are found in patients with performed DSA ,some of them C4d stain negative for SAMR.
In cardiac transplant , 15 years graft survival at 52% in those who de novo antibodies during first year post transplant while 15 year graft survival at 40% in those de novo DSA developed after one year post transplant, the latter associated with poor outcomes and grade 3 , worse ACR.
De novo antibodies productions cause subclinical AMR which associated with long term graft dysfunction with negative outcomes which developed later .
Development of de novo DSA in renal transplant directed at class II donor HLA mismatches which predicts kidney graft loss.
Patient survival decreased at 5 years post-transplant in DSA positive patients compared to DSA negative patients.
In liver transplantation, it is difficult to identify early AMR due to
– lack of clear clinical , histology cal and immunohistological cretria for diagnosis of AMR.
– nonspecific clinical and pathological findings of cholestasis similar to AMR.
Recipients that maintain positive crossmatch are at high risk of AMR.
Studies shown as regard to relation between DSA and chronic rejection using MFI ,performed class I antibodies more determental to graft survival than class II antibodies.
Pancreatic transplantation, there is association between post transplant DSA and decreas graft survival and increase incidence of rejection.
Long term pancreatic graft survival is inferior to survival of other solid organ as diagnosis of pancreatic is clinically complex.
Presence of pre-transplant DSA in islet cell transplantation associated with poor outcomes after transplantation.
In lung transplantation, presence of anti-HLA antibodies associated with bronchitis obliterating syndrome which cause poor prognosis and short graft survival.
In cardiac transplantation , cardiac allograft vasculopathy ,primary cause of death in long term heart transplant survivors due to complement activation and fixation in graft endothelium .
Presence of C1q+ DSA after transplantation had AMR at next biopsy ( have C4d deposition) suggests that DSA monitoring is effective in predicting AMR .
C1q assay is designed to detect immunoglobulin G IgG which fix complement.
Post transplantation monitoring ,a lot of patients who were DSA negative pre-transplant develop DSA post- transplant.
Serial monitoring of alloantibodies post-transplantation help in early diagnosis of chronic rejection and early identification of patients who are at risk of rejection due to non-compliance with immunosuppressive medication.
SAB luminex is highly sensitive to detect DSA even with low level which can put patient in risk of rejection.
References:
1. OPTN & SRTR 2010 Annual Data Report. http://www.srtr-org/annual_reports/2010 Accessed 20 May 2012.
2. Sutherland SM et al. Complement-fixing donor-specific antibodies identified by a novel C1q assay are associated with allograft loss. Pediatric Transplantation 2011.
3. Dunn TB, et al. Revisiting traditional risk factors of rejection and graft loss after kidney transplantation.
American Journal of Transplantation 2011.
4. Colvin RB, et al. Antibody-mediated organ allograft rejection. National Review of Immunology 2003; 5(10): 807-817.
5. Kaczmarek I, et al. Donor-specific HLA alloantibodies: long-term impact on cardiac allograft vasculopathy
and mortality after heart transplant. Experimental and Clinical Transplantation 2008; 6: 229-235.
6. Issa N, et al. Transp ation 2008: 86(5): 681-685.
7. Terasaki, et al. Humoral theory of transplantation. American Journal of Transplantation 2003; 3: 665-673.
8. Kimball PM, et al Surveillance of alloantibodies after transplantation identifies the risk of chronic
rejection. Internal Society of Nephrology 2011 ; 79: 1131-1137.
9. Lefaucheur, et al. Clinical relevance of preformed HLA donor-specific antibodies in kidney
transplantation. American journal of transplantation : official journal of the American Society of Transplantation and the American Society of Transplant Surgeons 2008; 8(2): 324-331.
10. Wiebe C, et al Evolution and clinical pathologic correlations of de novo donor-specific HLA antibody post kidney transplant. American Journal of Transplantation 2012; 12: 1157-1167.
11. Yabu JM, et al. C1q-fixing human leukocyte antigen antibodies are specific for predicting transplant glomerulopathy and late graft failure after kidney transplantation. Clinical and Translational Research 2011; 91 (3):342-347.
1. In your own words, summarise the role of anti-HLA Antibodies in Transplantation.
AMR
Anti-Human Leukocyte Antigen (HLA) DSA are either preformed( with blood transfusion, previous transplant, or pregnancy or Denove And are associated with AMR, graft failure, poor graft and patient survival.
preformed DSAs are usually associated with early acute AMR, chronic rejection, and subclinical rejection (without immediate apparent graft dysfunction). on the other hand Denovo DSAs are associated with early and late acute AMR, chronic and subclinical AMR
development of chronic renal failure isa leading cause of renal allograft failure.(1) Chronic Rejection due to de novo DSA from the start or complicating acute AMR, Patients with preformed DSA and those who develop de novo DSA are at an increased risk of having chronic rejection.
The early identification and subsequent removal of clinically harmful DSA associ- ated with AMR, both pre- and post-transplant, may prevent allograft loss (1)
In KTx numerous studies demonstrated that de novo DSA against Class II donor HLA mismatches development , is associated with poor out-comes (2)
Liver Transplantation: DSA was an independent predictor of poor patient survival and was associated with AMR (3)
Denovo DSA associated with chronic rejection , with the Anti class I DSA beingare more significant with negative outcomes.
Pancreas Transplantation:
post-transplant denovo DSA increased incidence of rejection and decreased graft survival.
Islet Cell and Multi-Visceral Transplantation
pre-transplant DSA is associated with poor outcomes postransplant.
Lung Transplantation
DSAs are associated with a higher prevalence of BOS (Bronchiolitis Obliterans Syndrome) with poor graft and patient survival.
2. How would you monitor DSA post-transplantation?
Serial monitoring of DSA is more valuable than single-point testing,
DSA monitoring
1) C1q assay
Some of the DSAs are complement fixing (Ig G) , others are non complement fixing not causing rejection, C1q (+) used in monitoring of complement fixing DSAwere significantly significantly associated with graft rejection and more likely to have C4d deposition in biopsy.
2)Luminex®-based single-antigen beads (SAB)
Value :
1) discrimination between donor-specific and non-donor-specific antibodies
2) highly sensitive thus detecting low level DSA which can still put patients at risk for rejection
3) detect Changes in DSA specificities or the appearance of new DSA that predect an early rejection process
Post-transplantation Monitoring
1) predicting AMR
2) Early identification of DSA through routine monitoring, helps the early initiation of anti-hu-
moral therapy as a result clearance of DSA and improvement of the overall survival rates.
3) Serial facilitate early diagnosis of chronic rejection.40
4) identification of patients at risk for rejection due to insufficient immunosuppression due to nonadherence to immunosuppressivemedications
5) adjustment of immunosuppressive therapy post-transplant.
References:
(1) Kimball PM, et al Surveillance of alloantibodies after transplantation identifies the risk of chronic rejection. Internal Society of Nephrology 2011 ; 79: 1131-1137.
(2) Fotheringham J, et al Natural history of protienuria in renal transplant recipients developing de novo human leukocyte antigen antibodies. Clinical and Translational Research 2011; 91 (9): 991-996.
(3) Kozlowksi T, et al Liver allograft antibody-mediated rejection with demonstration of sinusoidal C4d staining and circulating donor-specific antibodies. Liver Transplantation 2011; 17: 357-368.
In spite of potent immunosuppression long-term graft survival has not improved recently due to DSAs resulting in AMR.
To prevent graft loss,determining preformed or de Novo DSA is helpful. Acute AMR isoften caused by preformed DSAs but late or chronic AMR by denov DSAs.Another type of AMR is subclinical AMR which is not associated with immediate graft dysfunction,could deteriorate long-term graft functio. Subclinical AMR could be seen with both types of DSA (preformed or de Novo ) and maybe C4d isnegative and is related to non- adherence. De novo DSAs could progress from subclinical injury with pertubular capillaricapillaries +/- c4d, glomerulitis to IFTA +/- transplant glomerulopathy with increased creatinine and proteinuria, causing graft loss. They are usually against class II of honor HLAs .C1q (+)DSAS are capable of fixing complement so theyare 6times more harmful .The most sensitive method for DSA monitoring is luminex SAB .Early detection and treatment of de Novo DSAs results in decline in their titer by90%
-The primary cause of graft loss is late anti-body mediated rejection (AMR).
– DSA was defined as preformed antibodies present in the recipient’s serum against donor’s HLA antigens, these formed pre-transplant as a result of a sensitization event (blood transfusion, previous transplant, or pregnancy).
– Recently, there is a trend toward monitoring for the post-transplant development of antibodies directed against donor-specific HLA class I and class II mismatches. The DSAs whether detected pre- or post-transplant, if not treated, increase the risk of graft loss and/ or rejection. Because DSA attacks the endothelium of the allograft causing AMR.
–DSAs responsible for AMR are either preformed DSA which largely causes early acute AMR rejection and De novo DSA which, is responsible mainly for a late AMR and to a lesser extend to early AMR. AMR significantly lower graft survival.
-DSA can cause subclinical antibody-mediated rejection (SAMR) which associated with poor long-term graft function. SAMR is caused by preformed DSA and some of which are C4d stain negative.
-the range of dnDSA post-transplant is 24% to 62% with the highest level in liver transplantation.
-the graft survival decrease with the presence of anti-HLA II antibodies and their level also impact the graft survival, as a high level is associated with low graft survival. C4d stain TG has the lowest graft survival as compared with C4d negative.
DSA is Predictive of Lower Patient Survival:
Not only the graft survival but also the patient survival affected by the presence of anti-HLA antibody. DSA was an independent predictor of poor patient survival
-in liver transplantation there is suggestions to diagnose AMR in liver transplant, based on the presence of DSA in the recipient serum. Preformed class I antibodies was found to be more determined to graft survival than class II antibodies. Detection of de novo DSA in the first year put the patient at high risk of graft rejection, especially in C4d positive recipients.
-in a study reported by Yabu et al., the presence of C1q (+) DSA 6 times more likely to lose their grafts due to allograft rejection and more likely to have C4d positivity on biopsy, than patients with C1q (-) DSA.
-serial monitoring of these antibodies helps diagnosis of chronic rejection. Routine monitoring of DSA may provide early identification of patients at risk for rejection and may be useful in dose adjustment of the immunosuppressive therapy. Early identification of DSA can predict AMR occurrence, allowing for initiation of specific treatment sooner, to clear these DSA and ultimately improve graft survival.
– (SAB) is a highly sensitive tool, can discriminate between donor-specific and non-donor-specific antibodies. It has the advantage to detect a low level of DSA that can increase the risk of rejection and can detect new DSA and changes in DSA.
–
The Role of anti-HLA Antibodies in Transplantation?
● in pre transplantation in the past the concept of hla ab was precisely to sensitization but nowadays it is concerned with any antigen in doner to which patient devolp ab
the presence of antibodies
directed against antigens expressed on donor organs, when not treated clinically, results in an immune attack on the transplanted organ, and increases risk of graft
loss and/or rejection. DSA attacks the endothelium of the allograft, resulting in subsequent AMR.4,5 The progression of DSA development and thecorresponding clinical events compound to damage the allograft, resulting in chronic changes over time that ultimately compromise graft function and survival.
●How would you monitor DSA post-transplantation?
C1q assay may prove to be important in optimizing post transplant care.
Luminex-SAB is the most sensitive allow for a precise, highly sensitive determination of a patient’s antibody profile. This makes discrimination between donor-specific and non-donor-specific antibodies possible.
Other methos fc , elisa and cdc .
Although there is great advances in renal transplantation yet the long term graft survival is sub optimum , AMR is a major cause of post transplant graft loss .
DSAs which was historically defined as pre formed circulating anti HLA antibodies, has a main role in development of AMR .
DSAs could develop post transplant and are called denovo DSAs and are associated with higher rates of graft failure .
Presence of DSAs doesn’t only affect graft survival , but also patient survival .
Rejection caused by DSAs may be subclinical , hyperacute or acute AMR .
The detection of anti-HLA antibody in transplant recipients allows the clinician to better predict AMR in
the post- transplant period .
Not all DSAs are clinically relevant for organ transplantation, mainly the complement fixing antibodies are clinically important.
C1q assays, detect the complement fixing DSAs before tx .
Post transplant monitoring of DSAs is essential as it may help prediction of AMR , allow adjusting IS of at risk patients ,allowing early clearance of DSAs improving survival of graft .
Luminex based SAB is the best for DSAs monitoring post transplant.
The frequency of monitoring is based upon patient risk
Early identification and elimination of DSAs significantly improves survival of graft and the patient
the role of anti-HLA antibodies in transplantation
Although there are significant improvements in post-transplant care, maintaining long term graft function is a big challenge. The primary cause of graft loss is late anti-body mediated rejection (AMR). In the past, DSA was defined as preformed antibodies present in the recipient’s serum against donor’s HLA antigens, these formed pre-transplant as a result of a sensitization event (blood transfusion, previous transplant, or pregnancy). Recently, there is a trend toward monitoring for the post-transplant development of antibodies directed against donor-specific HLA class I and class II mismatches. The DSAs whether detected pre- or post-transplant, if not treated, increase the risk of graft loss and/ or rejection. Because DSA attacks the endothelium of the allograft causing AMR.
In order to prevent allograft loss, identification and subsequent removal of harmful DSA that cause AMR in both pre-and post-transplant courses. Sold-phase assays are both sensitive and specific tools for the accurate identification of DSA.
The Spectrum of Antibody-Mediated Rejection:
DSAs responsible for AMR are either preformed DSA which largely causes early acute AMR rejection and De novo DSA which, is responsible mainly for a late AMR and to a lesser extend to early AMR. AMR significantly lower graft survival.
Subclinical Antibody-Mediated Rejection:
DSA can cause subclinical antibody-mediated rejection (SAMR) which, may not be associated with an impairment of graft function. But, it is associated with poor long-term graft function. SAMR is caused by preformed DSA and some of which are C4d stain negative. Non-adherence to immunosuppressive drugs are
De Novo DSA in Post-Transplant Solid Organ Transplant Recipients
The range of dnDSA post-transplant is 24% to 62% with the highest level in liver transplantation.
In cardiac allograft, the development of dnDSA has been associated with decreased graft survival either during or after the 1st year post-transplantation.
In kidney transplant recipients, DSA develops mainly against Class II donor HLA mismatches. It is associated with poor outcomes.
DSA is Predictive of Lower Graft Survival:
The development of HLA antibodies predict graft survival, and as the time elapsed post-transplant the risk of AMR increases with the presence of anti-HLA-Class II antibodies.
Effect of DSA on Renal Allograft Survival:
Renal graft survival is lower in the presence of de novo DSA when compared with those without de novo DSA.
The Effect of Transplant Glomerulopathy (TG) on Renal Allograft Survival:
The graft survival decrease with the presence of anti-HLA II antibodies and their level also impact the graft survival, as a high level is associated with low graft survival. C4d stain TG has the lowest graft survival as compared with C4d negative.
DSA is Predictive of Lower Patient Survival:
Not only the graft survival but also the patient survival affected by the presence of anti-HLA antibody. DSA was an independent predictor of poor patient survival
Liver Transplant:
The diagnosis of an early AMR in liver transplant recipients is difficult, due to the lack of clear criteria for diagnosis as well, the result of crossmatch at the time of transplantation. recently, there is suggestions to diagnose AMR in liver transplant, based on the presence of DSA in the recipient serum. Preformed class I antibodies was found to be more determined to graft survival than class II antibodies. Detection of de novo DSA in the first year put the patient at high risk of graft rejection, especially in C4d positive recipients.
Pancreas Transplantation:
The development of post-transplant DSA is significantly associated with poor outcomes. It is considered an independent risk factor for graft survival by many studies.
Islet Cell and Multi-Visceral Transplantation:
The presence of preformed DSA put the recipient at high risk of rejection, so monitoring of DSA in these patients is a valuable diagnostic tool for early diagnosis and treatment of acute rejection.
Lung transplantation:
Bronchiolitis Obliterans Syndrome (BOS) is a serious complication of lung transplantation leading to shorter graft survival. Its occurrence is strongly associated with the presence of anti-HLA antibodies. The presence of these antibodies precede the diagnosis of BOS by about 1.1 years.
Cardiac Transplantation:
Cardiac allograft vasculopathy (CAV) is the primary cause of death. The presence of DSA can result in complement activation and fixation on the graft endothelium, leading to graft loss and death.
The Future of DSA Monitoring: Effect of C1q DSA on Allograft Survival
Anti-HLA antibody monitoring can help the clinician to better predict AMR in the post-transplant patient. Complement fixing antibodies are more relevant to organ rejection and their detection important in order to treat transplant patients properly. A novel C1q assay perfectly detects complement-fixing antibodies and in combination with other methodologies can define the patient’s immunologic profile. Patients with C1q (+) DSA after transplant had AMR at the next biopsy, suggesting DSA monitoring is effective in predicting AMR.
In a study reported by Yabu et al., the presence of C1q (+) DSA 6 times more likely to lose their grafts due to allograft rejection and more likely to have C4d positivity on biopsy, than patients with C1q (-) DSA.
Post-Transplantation Monitoring:
Many DSA negative recipients develop DSA within 2 years post-transplantation. serial monitoring of these antibodies helps diagnosis of chronic rejection. Routine monitoring of DSA may provide early identification of patients at risk for rejection and may be useful in dose adjustment of the immunosuppressive therapy. Early identification of DSA can predict AMR occurrence, allowing for initiation of specific treatment sooner, to clear these DSA and ultimately improve graft survival.
Graft survival in recipients in whom DSA persist is worse than those who had cleared the DSA.
Why monitor DSA post-transplantation:
1- Allograft survival can be predicted.
2- > 40% of kidney transplant recipients with AMR develop transplant glomerulopathy.
3- Recipients diagnosed with transplant glomerulopathy have a 5-year graft survival rate less than 50% from the time of diagnosis.
4- Early antibody developers have less graft survival.
5- De novo DSA in cardiac transplant recipients are highly associated with decreased survival especially worse in those with persistent DSA.
6- Non-adherence to immunosuppression is a major factor in the development of de novo DSA
7- Inadequate immunosuppression contributes to de novo DSA and AMR that can be C4d negative
Why monitor with single bead antigen:
Luminex based single-antigen beads (SAB) is a highly sensitive tool, can discriminate between donor-specific and non-donor-specific antibodies. It has the advantage to detect a low level of DSA that can increase the risk of rejection and can detect new DSA and changes in DSA.
Optimizing DSA Monitoring Strategies: DSA monitoring is increasingly suggested as a standard of care in transplantation. the frequency of monitoring will be patient-specific according to individual risk for AMR. Serial monitoring is more valuable than a single monitoring test.
Conclusion:
The transplantation field show several advancements since its beginning. Most recently, many data indicate the use of DSA monitoring in post-transplantation as an important tool in the management of these patients. And the routine monitoring of DSA in the post-transplant cases offers promise in long term graft and patient survival
Summary :
Detection of Anti-HLA antibodies in the recipient serum pre-transplantation affect the decision of transplantation, precede or not with that donor. Risk classification of the recipient (rejection risk). Choice of immunosuppression protocol either the induction or the maintenance therapy. And the use of desensitization protocol.
Post-transplantation monitoring of the DSA can predict rejection. Offer therapy to clear these DSA can improve graft survival. Help in immunosuppression dose adjustment.
with the advanced Luminex assay more precise detection of DSA become possible
Though there’s significant improve improvements in post-transplant care, long term graft
function is less than optimal.
In the United States, adjusted 10 year allograft survival rates for deceased and living
donor kidney transplants are only 40.8% and 57.9%, respectively.
AMR leading to Late stage graft failure, secondary to antibody is a main cause of poor
graft survival.
Patient survival is also significantly decreased at 5-years post-transplant in DSA positive
patients compared to non DSA patient.
Monitoring of DSA either do novo or primary is important in transplant.
DSA, when not treated clinically, results in an immune attack on the transplanted organ,
and increases risk of graft loss and/or rejection.
DSA attacks the endothelium of the allograft, resulting in subsequent AMR.
Anti-HLA antibodies contribute to the development of chronic renal failure, the leading
cause of renal allograft failure.
The early identification and subsequent removal of clinically harmful DSA associated
with AMR, both pre- and post-Transplant aid in salvage of graft.
Early acute process: often lead to acute rejection
Chronic AMR: Patients with preformed DSA and those who develop de novo DSA are at an increased risk of having chronic rejection.
Subclinical antibody mediated rejection:
DSA may also develop without an immediate impairment of graft function. This type of
rejection, or subclinical antibody mediated rejection (SAMR), has been reported to have
an impact on long-term graft dysfunction and deterioration.
The development of de novo donor-specific HLA antibodies post-transplantation has
been associated with higher graft failure rates. The range of dn DSA is 24% to 62% with
the highest presence in post liver transplant recipients.
Monitoring DSA :
Research has suggested that the evaluation of the C1q assay provides a further layer of
immunologic antibody information that may prove to be an adjunct in optimizing post-
transplant care.
kidney transplant recipients with C1q (+) DSA were nearly 6 times more likely to lose
their grafts than those with C1q (-) DSA.
routine monitoring of DSA may provide early identification of those patients at risk for
rejection due to insufficient immunosuppression as a result of poor compliance with
immunosuppressive therapy. DSA monitoring may be useful in the adjustment of
immunosuppressive therapy post-transplant.
Why monitoring?
10 years graft Survival is less in early antibody developer than late .
40%develope TG.
Patient with TG experienced 5-year graft survival rates less than 50% from the time of
diagnosis.
Many patient developed de novo DSA secondary to non-adherence to
immunosuppressive therapy. Insufficient immunosuppression may contribute to the
development of de novo DSA and AMR secondary to misclassifications based on C4d
negativity.
The use of Luminex® SABs a provides a number of advantages, including:
• The presence of low-level DSA can put patients at risk for rejection
• Changes in DSA or the appearance of new DSA specificities may reveal an early
rejection process.
Optimizing DSA Monitoring Strategies:
Choosing a monitoring frequency based on a patient’s individual risk of developing AMR
post-transplant will be the most efficient and clinically relevant strategy.
Serial monitoring of DSA is more valuable than single measure.
Post transplantation Group :
(a) High-risk patients (i.e., desensitized or DSA positive/XM negative) should be
monitored by measurement of DSA and protocol biopsies in the first 3 months after
transplantation.
(b) Intermediate-risk patients (history of DSA but currently negative) should be monitored
for DSA within the first month. If DSA is present, a biopsy should be performed.
(c) Low-risk patients (no sensitized first transplantation) should be screened for DSA at
least once 3 to 12 months after transplantation. If DSA is detected, a biopsy should be
performed.
In all three categories, the recommendations for subsequent treatment are based on the
biopsy results.
Anti HLA Ab are formed against HLA Ag during pregnancy, blood transfusion or previous transplantation. It associated withy increase risk of hyper acute & acute antibody rejection. So presence of preformed DSA associated with decrease the chance of obtaining compatible donor. Anti HLA Abs can be directed to private specificities (HLa-A1) or public specificities ( Bw6).
Nowadays anti-HLA DSA considered the most significant biomarkers for prediction of graft failure. The exact characterization of anti-HLA DSA as complement binding capacity & IgG subclasses can add more benefit for prediction of graft outcome. Consensus guidelines in 2013 for post transplant screening for DSA recommend the following:
After I year post transplantation, measuring of DSA is not routinely done unless there is graft dysfunction, non adherence, or change in immunosuppression.
References:
1- The presence of antibodies directed against antigens expressed on donor organs attacks the immune system on the transplanted organ and increases the risk of graft loss or rejection. In addition, DSA attacks the endothelium of the allograft, resulting in subsequent AMR. Repeated attacks of such alloantibody-mediated injury result in distinct changes in the microvasculature of the allograft and development of chronic rejection and have been associated with a higher graft failure rate.
The development of de novo antibodies during and after the first year post-transplant has been shown to significantly reduce the 15-year graft survival in cardiac allografts recipients. Moreover, it was associated with a higher incidence of sub-clinical AMR, leading to long-term graft dysfunction. Similarly, de novo DSA is associated with poor outcomes in renal transplant patients, liver, lungs (leading to Bronchiolitis Obliterans Syndrome (BOS)), and pancreas recipients.
2- DSA Monitoring: Many transplant recipients are DSA (-) pre-transplant and develop DSA post-transplant, typically within the first two years. Serial monitoring of anti-HLA antibodies in transplant recipients may facilitate early diagnosis of chronic rejection. Moreover, it is of great value in adjusting immunosuppressive therapy post-transplant and initiating anti-humoral therapy once DSA is detected, allowing for early clearance of DSA, hence improving the overall allograft survival rates. Serial monitoring of DSA is more valuable than single-point testing.
A novel C1q assay is designed to detect immunoglobulin G (IgG) antibodies that can fix and activate complement. C1q (+) DSA estimation had proven its high efficacy in several studies in predicting AMR, before allograft damage has been ensued, in several publications, including pediatric heart transplant recipients and kidney transplant recipients. Patients with C1q (+) DSA were significantly more likely to have C4d deposition on biopsy. Additionally, patients with C1q (+) DSA were nearly six times more likely to lose their grafts than those with C1q (-) DSA.
De novo DSA is associated with poor graft survival. it can lead to early acute AMR or can lead to chronic AMR and graft failure.
DSA can lead to subclinical rejection without immediate graft dysfunction but on the long term can lead to transplant glomerulopathy and graft failure.
So the presence of DSA is associated with lower patient and graft survival.
monitoring for DSA is important to detect them early before graft damage so we can optimize immunosuppression and emphasize on adherence to immunosuppressive drugs.
Low risk patients should be monitored at least once during 3 -12 months post transplant and then once a year. for those with higher risk should be monitored more frequently.
B cells and plasma cells activation cause DSA activation which is the leading cause of AMR by activation and binding to HLA and non HLA Ab leading to transplant glomerulopathy and initiation of AMR with it’s different forms: hyperacute, early and late acute AMR and chronic ABMR.
Most sensitized patients have DSA level pretransplant known as performed DSA occurs due to different causes the other type is denovo DSA occurs late after transplantation responsible for late acute AMR with poorer outcome than the performed DSA,DSA level can be affected by type of induction and immunosuppressive protocols this will also cause better graft function and prevention of rejection.
DSA cause damage to the graft either by complement activation, C1q binding or direct effects on endothelial cells and Ab mediated cytotoxicity, all these mechanisms are affected by DSA class ,strength of C1q and IgG subclasses(IgG3 is most effective and capable to bind to C1q and can cause early graft loose), studies showed the effect of C1q positive DSA on graft loss and acute rejection with C4D deposition.
DSA should be monitored for early detection and treatment of rejection most patients should be monitored every 2 _3 months in the first year post transplant then annually but in sensitized patients more frequent monitoring and graft biopsy is mandatory in risky patients .
DSA monitoring help to:
improve graft outcome
adjust immunosuppressants especially in non compliance patients
Detect low DSA titer even with absence of graft dysfunction
Detect new DSA or change in the level of preexisting DSA.
Reference
_clinical trials.gov. .(2021,March 9).Donor specific Anti_HLA antibodies monitoring in kidney transplant recipient. Retrieved from U.S.national library of medicine.
_ journal of immunology research. (2014,October 13).clinical relevance of HLA antibodies monitoring after kidney transplant. From Hindawi,Mario cleric.
The Anti HLA antibodies either preformed circulating antibodies or de novo DSA against HLA class I and class II present in the recipient’s immune system have a crucial role in long term graft survival. These antibodies directed against antigens expressed on donor organs, if not treated by desensitization results in an immune attack on the transplanted organ and increases risk of graft loss and rejection. DSA attacks the endothelium of the allograft, resulting in subsequent ABMR. Frequent attacks of ABMR resulting in chronic changes over time that ultimately impact graft function and survival. It has shown that up to 96% of rejected allografts develop some degree of DSA.
Sub-Clinical Antibody Mediated Rejection
Histological evidence of ABMR can be present without change in serum creatinine that due to subclinical Prescence of DSAs and this type of rejection reported to have an impact on long-term graft dysfunction. Typically, non-adherence to immunosuppressive therapy is associated with the histological finding reflecting the high frequency of de novo DSA.
De Novo DSA in Post-Transplant Solid Organ Transplant Recipients
De novo antibody production may cause subclinical ABMR that is associated with long- term graft dysfunction. Negative outcomes can take several years to occur after de novo antibody production. DSA is Predictive of Lower Graft Survival and risk of Transplant Glomerulopathy development depends on anti-HLA-II levels.
DSA is Predictive of Lower Patient Survival
There is a strong association between presence of of anti-HLA antibody and patient survival
Effect of C1q DSA on Allograft Survival:
Since not all anti HLA antibodies can fix complement, A novel C1q assay designed to detect immunoglobulin G (IgG) antibodies capable of fixing complement has been studied in the post-transplant setting. The presence of C4d negative ABMR biopsies make the C1q assay more important to get information regarding complement activation in ABMR process. Some studies have reported that C1q DSA have been associated with higher incidence of AMR and graft loss. In a study reported by Yabu et al., kidney transplant recipients with C1q (+) DSA were nearly 6 times more likely to lose their grafts than those with C1q (-) DSA.
Post-transplantation Monitoring
It is known that the antibodies need a long time to produce the chronic vascular changes that can result in graft failure. So the serial monitoring of HLA antibodies following transplantation may facilitate early diagnosis of chronic rejection and will guide to patients at risk for rejection due to insufficient immunosuppression as a result of poor compliance with immunosuppressive therapy.
Why Monitor With Single-Antigen Beads?
The fast-growing methods for detecting anti HLA antibodies making Luminex SABs is most sensitive method to detect anti HLA antibodies and being as part of a comprehensive monitoring program which can discriminate between donor-specific and non-donor-specific antibodies.
Optimizing DSA Monitoring Strategies
The frequency of post-transplant monitoring will be patient specific. Choosing a monitoring frequency based on a patient’s individual risk of developing AMR post-transplant will be the most efficient and clinically relevant strategy.
Detected pre and post transplantation DSA is associated with an increased risk of rejection and graft loss.
DSA attacks to the graft endothelium of allograft and results in AMR and over time leads to chronic changes that eventually comprise graft survival.
It has shown that up to 96% of rejected allografts develop some degree of DSA.
Since the presence of anti HLA antibodies correlates with kidney graft failure, early recognition of harmful DSA and removal of them may prevent allograft loss.
The spectrum of AMR
AMR is often either acute, resulting from anamnestic response and preexisting DSA or late or chronic due to de novo DSA (dn DSA).
Patients with performed DSA are at increased risk of acute AMR that is related to significantly lower graft survival. Chronic rejection, a leading cause of graft loss, is associated with both performed and de novo DSA.
Subclinical AMR
DSA can also be associated with subclinical AMR that has a deleterious impact on long term graft dysfunction. Negative outcomes can take several years after production of dnDSA.
Microcirculation inflammation that is more common in late kidney biopsies may reflect the high frequency of de novo DSA, although it is also a frequent finding with performed DSA.
De novo DSA
The development of dnDSA has been associated with higher graft loss. dnDSA is more frequent in post liver transplant recipients.
Development of DSAs after one year has been associated with worse graft survival compared to development of dnDSA during the first year after cardiac transplantation.
In kidney transplant patients, dnDSA predominantly directed at class II HLA, and is associated with poor outcomes.
The risk of chronic AMR increases with the presence of anti-class II HLA DSAs.
In addition to the impact of dnDSA on graft survival, the significant association of them with recipients’ survival has also been demonstrated.
In liver transplant patients, the presence of DSAs is associated with AMR and rejection, particularly class I antibodies. Furthermore, DSA is associated with negative outcomes, indicating that AMR may contribute to interlobular bile duct loss.
In pancreas transplantation, development of post-transplant DSAs has been associated with poor outcomes, and may be utilized as an independent risk factor for graft survival.
In the pancreas, islet cell transplantation, and multivisceral transplantation, the presence of DSAs indicates a high risk of rejection. Thus, DSA monitoring is a valuable tool for early diagnosis and treatment of AMR.
In lung transplantation, DSAs are associated with a higher prevalence of BOS, and it is crucial to detect DSA sooner.
In cardiac transplantation, circulating DSAs predispose patients to accelerate cardiac allograft vasculopathy, graft loss and death.
The effect of C1q assay
Since not all DSAs are complement fixing and may not be relevant to organ rejection, the C1q assay has been designed to detect IgG antibodies capable of fixing complement. The role of complement fixation, as detected by C4d staining in predicting AMR, is not widely accepted. The C1q assay may provide more immunological information for optimizing post-transplant care. Some studies have reported that C1q DSA have been associated with higher incidence of AMR and graft loss and the presence of C4d deposition biopsy.
Post-transplantation DSA monitoring
Many recipients that are DSA-, may develop DSA post-transplant, especially in the first 2 years after transplantation. Since it may take months to years that DSA production led to chronic vascular change, monitoring and early detection of DSAs may provide early identification of those patients at risk for rejection and with appropriate therapy may improve the overall survival rate. Persistent DSAs are associated with the worst survival.
Survival in early antibody developers (<1year) is better than late antibody developer.
More than 40% of kidney transplant recipients with AMR develop transplant glomerulopathy, and five-year survival in recipients with transplant glomerulopathy was less than 50%.
Non adherence and insufficient immunosuppression may contribute to development of dnDSA.
Luminex based SAB
SAB is a precise and very sensitive assay for detection of DSA, and provides discrimination between donor-specific and non-donor specific antibodies with a number of advantages: detection of a low level of DSA, detection of changes in DSA or the appearance of a new DSA that may reveal an early rejection process.
Optimizing DSA monitoring
Routine post-transplant DSA monitoring has been recognized as a standard of care practice, and monitoring frequency should be individualized based on patient’s individual risk of developing AMR. Serial monitoring of DSA is more valuable than single-point testing.
In your own words, summarize the role of anti-HLA Antibodies in Transplantation.
How would you monitor DSA post-transplantation?
Despite the improvement in the organ transplant still graft survival hampered by antibody mediated rejection (AMR), still the 10-year survival of LD and DD only 56%, 44% respectively based on the US-data registry. In another large cohort study reported 25% of recipients developed DSA post transplantation also performed DSA found in the range of 24-68% of transplantation and highest with liver transplantation.
Performed DSA more in sensitized patients (previous transplantation, blood transfusion, pregnancy), DSA can lead to subclinical acute rejection with normal allograft function (SMAR), which can impact the long-term graft survival and need years to show the effect on the graft, especially in recipients with poor compliance with IS.
Performed DSA For both class1, class11 can cause AMR, class1 HLA, in particular IgG2, IgG4 abs with typical endothelial injury and microvascular inflammation acute AMR and associated with poor graft survival while class11, Dn DSA associated with late and chronic ABMR, especially C4D+ TG which associated with worst graft survival.
15 years cardiac allograft survival in the presence of ds DSA is reduced to 52% in the first year ,40% after 1 year of TX, also associated with lower 5-year patient survival.
Pancreatic, lung and multi-visceral organ transplant had inferior graft survival with the performed DSA with increased risk of AMR.
In liver transplant performed anti- class 1 DSA in the first year associated with poor graft survival as compared with class2 and development of DSA after first year usually associated with chronic rejection, DSA+/diffuse C4d+ patients had a significantly higher frequency of ACR, with steroid resistant rejection, and bile duct injury
Both complement fixing DSAs like C1q associated with ABMR, and associated with 6-fold risk of graft loss, C1q -assay can help in predicting AMR with C4D staining is important for the diagnosis of AMR.
Post-transplantation Monitoring:
The incidence of chronic AMBR was not significantly dependent on the MFI value (Schinstock et al., 2017)also not all DSA lead to tissue damage, DSAs post-transplant may stays for years with stable graft function, Moreover, problems such as bead saturation, shared epitope, and prozone effect can lead to MFI values that differ from DSA levels, so the use of single antigen flow bead (SAFB) with antibody titration methods its more accurate to assess DSA intensity, (Velidedeoglu et al.,2018; Schinstock et al., 2020).
routine monitoring of DSAshould be considered as standard of care post transplantation as it helps with oyjer clinical indicators like creatinine and protienuria in early diagnosis of AMR, the frequency of DSA monitoring should be patient specific, those with low risk need less frequent monitoring while moderate and high-risk patients need more frequent assays (1,3,6,12 months ) post Tx then every year at any point patient had acute graft dysfunction with history ofpoor compliance with IS medication should perform the DSA assay with graft biopsy and treat accordingly
Patients with rising dn DSA level with in first 3 months post TX, should go for graft biopsy ,Sensitized patients with pre-transplantation DSAs,preferred frequent monitoring and protocol biopsy 3, 12 months.
Promising noninvasive molecular biomarkers:
still under investigation and need validation by large cohorts trails including:
1-IFN-γ enzyme-linked immunosorbent spot assay
2- donor-derived cell-free DNA (dd-cfDNA) assay. this test was validated for Acute Rejection diagnosis in Kidney Transplant Recipients (DART) study which included patients with active ABMR, chronic active ABMR, or TCMR With a cutoff of 1.0%, (Bloom et al., 2017). The combination of dd-cf-DNA with DSA monitoring increase the sensitivity and specificity for the diagnosis of Active AMBR, TCMR.
References:
1- Up to date medicine, DSA monitoring post transplantation
2- Therapies for Chronic Allograft Rejection: In Young Kim and Daniel C. Brennan *
Department of Internal Medicine, Johns Hopkins School of Medicine, Baltimore, MD, United States, published: 15 April 2021.
Donor Specific Antibody Monitoring
Role of Anti-HLA Antibodies in Transplantation
• Adjusted 10 year allograft survival rates for Deceased and living donor kidney transplantation in US are only 40.8% and 57.8%
• Anti-HLA is preformed circulating antibodies present in the recipient immune system which occurs due to sensitising phenomena such as blood transfusions, pregnancy and previous solid organ transplantation
• DSA and form against class 1 or 2
• DSA attacks the endothelium of allograft results in AMR
Spectrum of AMR
• Can occur as an early acute process – due to rapid response
• late and chronic process due to DnDSA
Subclinical Antibody mediated rejection
• occurs without an immediate deterioration of graft function
• have an impact on long term graft dysfunction and deterioration
• Lousy et al- happens winning 3. Months to 3years while chronic lesions steadily increases and significantly over 3 years
• micro circulation inflammation is commonly seen after 1 year kidney transplantations
• Non adherence to meds will have C4d stain negative SAMR
• dnDSA in post kidney transplantation usually directed against HLA class 2 and associated woth poor graft function
Prediction of lower graft survival
• the risk of developing chronic rejection leading to AMR increases with presence of Class2 antibodies
• The presence of C4d and positive TG or anti HLA-2 has the worse renal graft survival
• The presence of dnDSA has worse renal graft survival
DSA as patient survival predictor
• Presence of anti-HLA antibody and patient survival has been studied
• Dunn et al- DSa positive patient had reduced actuarial survival at 5 years post transplantation
• Smith et al – dnDSA is independent predictor of poor patient survival
DSA monitoring and effect of C1q DSA on allograft survival
• C1q able to detect IgG antibodies and capable of fixing complement
• All C1q+DSA had AMR at next biopsy proved that it able to predict AMR
• C1q provides a further layer of Immunologic antibody information that may important to be an adjunct in optimising post-transplant care
• Abu et al- C1q+ DSA has 6 times more risk in losing the grafts than C1q-
• Chin et al-C1q+DSA after transplantation had AMR at the protocol biopsy proved that complement binding DSA able to predict AMR
• C1q+ DSA associated with greater incidence of acute allograft rejection and more likely to have C4d deposition in renal biopsy
Post transplantation monitoring
• Usually Develop DSA after 2 years of the transplantations
• 50% of AMR has been missed as it may take years to produce chronic vascular changes that leads to graft failure
• DSAA monitoring may help in early identification of patient with risk of rejection due to suboptimal IS due to non adherence
• DSA can be useful in adjustment of IS
• Early identification of DSA and sooner in starting anti-humoral therapy will improve overall survival rates
• Survival is better in those who had cleared DSA than those who had persistent DSA
Why Monitor DSA post transplantation
• 10 year renal allograft survival in early antibody developers (40% of kidney transplant receivers with AMR had TG
• Solid organ transplant recipient with TG had <50% 5 year graft survival
Luminex
• Detects low level DSA which may put patient at risk of rejection
• Highly sensitive in determination of a patient’s antibody profile
• Change in DSA or newly formed DSA may reveal an early rejection process
The role of anti-HLA antibodies in transplantation:
-Preformed Anti-HLA antibodies were the result of pretransplant sensitization(blood transfusion, previous transplant, or pregnancy).
-Post-transplant Anti-HLA antibodies direct against donor-specific HLA class I and class II mismatches.
-Pre or post-transplant Antibodies increase the risk of rejections and poor patient and graft survival.
– Preformed DSA leads to acute AMR and lower graft survival.
-Large cohort studies showed 25% of transplant recipients have antibodies while previous renal transplant data have shown up to 96% of rejected allografts develop some level of detectable DSA.
-Anti-HLA antibodies contribute to the development of chronic renal failure that leads to renal allograft failure.
Sub-clinical antibody-mediated rejection :
– De novo DSA may develop without an immediate impairment of graft function that leads to sub-clinical antibody-mediated rejection(SAMR) and graft deterioration and long-term graft dysfunction.
-SAMR is associated with microcirculation inflammation.
-It is due to non-adherence to immunosuppressive therapy.
-The range of de novo DSA post-transplant is 24% -62% with the highest presence in post-liver transplant recipients.
-De novo DSA in renal transplant, predominately directed at class II donor HLA mismatches and associated with poor outcomes.
Effect of C1qDSA on allograft survival:
-Not all DSAs are complement-fixing
-C1q assay can detect IgG capable to fix and activate complement.
– Recipients with C1q(+)DSA have a high incidence of acute allograft rejection and are more likely to have C4d deposition found on biopsy.
Post-transplantation monitoring of DSA:
-Many transplant recipients develop de novo DSA within 2 years of transplant.
Advantages of DSA monitoring
1 .monitoring of DSA can facilitate early detection and diagnosis of chronic rejections.
2. Early identification of recipients at risk for rejection due to insufficient immunosuppression due to poor compliance with immunosuppressive therapy.
3. Can be useful in the adjustment of immunosuppressive therapy post-transplant.
4. Help in the precise adjustment of anti-humoral therapy and better outcomes.
-Luminex-based single-antigen beads allow for a precise, highly sensitive determination of the patient,s antibody profile and can detect a low level of DSA.
-The frequency of post-transplant monitoring will be patient-specific and serial monitoring more valuable than a single test.
– Kimball et al .preformed DSA against HLA class I and II decline by 90% at 6 months and undetectable at 1 year with effective treatment.
DSAs are antibodies directed against antigens expressed on donor organs, they can develop in the transplant recipient pre or post transplantation, usually they attack the endothelium on the allograft resulting in AMR.
They are associated with graft rejection, graft loss and lower patient survival.
At any given time, 25% of transplant recipients have DSAs. 96% or renal transplant recipients with rejected allografts develop some level of detectable DSA.
Early identification and removal of clinically harmful DSA associated with AMR, pre- and post transplant, may prevent allograft loss.
Pateints with preformed DSAs are at greater risk of acute AMR and lower graft survival.
Patients with preformed DSAs and de novo DSAs are at increased risk of chronic rejection.
Subclinical AMR typically is associated with non-adherence to immunosuppressive therapy and usually associated with preformed DSAs and negative C4d stain.
De novo DSAs have been associated with higher graft failure, they are more common in liver transplantation (62%), and less common with kidney-pancreas transplant patients.
De novo DSA development in renal transplant recipients, predominantly directed at class II donor HLA is associated with poor outcome and is detectable well before graft failure.
In liver transplant recipients, the presence of de novo DSA within the first year of liver transplantation was more common in recipients presented with chronic rejection, 92% of them had detectable DSAs before graft failure.
DSA+/diffuse C4d +>>>higher frequency of acute cellular rejection and steroid resistant rejection.
The role of DSA follow up in pancreas and multi-visceral transplantation is a valuable diagnostic tool in diagnosis and treatment of acute rejection.
DSA+ in lung transplant recipients is associated with higher prevalence of bronchiolitis obliterans and shorter graft survival. In cardiac transplantation it is associated with accelerated cardiac allograft vasculopathy and death.
Renal transplant recipients with C1q + DSA were nearly 6 times more likely
to lose their grafts than those with C1q – DSA.
Benefits of monitoring DSA post renal transplantation:
1- Early identification for those at risk of rejection especially due to non-adherence to immunosuppressive drugs.
2- Adjustment of IS drugs post transplantation.
SAB Luminex allow for precise determination of the patient’s antibody profile.
Makes discrimination between DSA and non-DSA possible.
Can detect low level DSA which increases the risk of rejection.
Detect changes in DSA or new DSA specificities which can reveal early rejection process.
How to Monitor DSA post transplantation:
DSA should be done in all RTx recipients at least one time in the first 3-12 months post transplant depending on their risk (low, standard, and high)
For subsequent determination:
DSA follow up periodicity can be modified if any of the following:
With the continuum of acute, late, and early chronic rejection contrary to previous thoughts of T cell role as the only important factor, It was proved that DSA’s either previously performed or Denovo formed to have a key role in transplant rejection. acute rejections may be of more favorable effect because of early detection as patients are monitored more frequently especially through first-year post-transplantation. later chronic rejection may be clinically evident after fibrotic changes that are irreversible. during follow-up, the gradual increase in creatinine level may be attributed and sometimes confused because of many factors that may be falsely considered as the cause (drugs dose, trough level, infections, dehydration, etc.)
With advanced technology and the revolution of single-antigen detection, we are now able to detect and intervene with rejections.
Routine testing in the first year in highly sensitized cases is essential.
Any unexpected change in eGFR should alert us.
DSA either preformed or denovo has imprtant in graft outcome .
25% of all kidney transplant has DSA , 60% graft rejection has DSA .
There is strong relationship between development of DSA and occurence of chronic graft failure .
DSA monitoring will help to diagnose subclinical AMR which has an impact on graft function outcome . subclinical AMR is closely related to drug non adherence .
development of denovo DSA is associated with higher incidence of graft failure .
negative effect of denovo DSA on graft may need years to appear .
in addition to rejection and graft loss ANTI HLA ab is demonstrated to be related with patient survival .
frequency of DSA monitoring is still not settled and it is depend on the patients degree of risk . the highest risk the more frequent monitoring is needed .
post-transplant care has improved, although graft function is still suboptimal. For dead and live donor kidney transplants, the adjusted 10-year allograft survival rates are only 40.8 and 57.9%, respectively.
Antibody-mediated rejection (AMR) is a major cause of late-stage graft failure.
Prior to transplantation, anti-Human Leukocyte Antigen (HLA) antibodies were characterized as preexisting circulating antibodies present in the recipient’s immune system (blood transfusion, previous transplant, or pregnancy).
It has recently become popular in the transplant community to check for clinically relevant antibodies directed against donor-specific HLA class I and class II mismatches.
Antibodies directed against antigens produced on donor organs result in an immunological assault on the transplanted organ, increasing the likelihood of graft loss and/or rejection.
DSA affects the allograft endothelium, causing AMR. Allograft deterioration is caused by continuous changes in DSA development and clinical events that eventually limit graft function and survival.
Preformed DSA may result in immediate hyperacute rejection and graft necrosis, as well as early acute ABMR and graft necrosis.
The development of de novo DSA may result in late acute ABMR, chronic ABMR, and transplant glomerulopathy. A variety of DSA properties, including as HLA classes, specificity, strength, IgG subclasses, and complement binding ability, influence the clinical manifestations of ABMR.
Those in the low-risk category ( no DSA prior to transplant) should have their DSA checked at least once every 3 to 12 months for the first 3 to 12 months after transplant.
In the Intermediate risk category the DSA should be checked In the first month after transplantation, check the DSA.and if any one of the following( change in immunosuppression, graft dysfunction, non-adherence to the medication) .
In high risk category DSA should be conducted on a regular basis at 1, 3, 6, and 12 months following Tx, and then once a year afterwards.
The Role of anti-HLA Antibodies in Transplantation
Anti-HLA ABs can be defined as the preformed circulating antibodies present in the recipient’s immune system which were the result of a sensitization event pre-transplant (blood transfusion, previous transplant, or pregnancy).
Whether detected pre- or post-transplant, the presence of antibodies directed against antigens expressed on donor organs, when not treated clinically, results in an immune attack on the transplanted organ, and increases risk of graft loss and/or rejection.
There is strong evidence that anti-HLA antibodies contribute to the development of chronic renal failure, the leading cause of renal allograft failure
The early identification and subsequent removal of clinically harmful DSA associated with AMR, both pre- and post-transplant, may prevent allograft loss.
offers highly sensitive and specific solid-phase assays allowing for the accurate identification of DSA both pre- and post- transplant.
Antibody-mediated rejection has 2 mode of occurrence:
Early and acute due to preformed ABs
Late and chronic due to denovo ABs(DSA)
DeNovo DSA also can lead to early acute rejection.
Patients with preformed DSA and those who develop de novo DSA are at an increased risk of having chronic rejection.
Sub-Clinical Antibody Mediated Rejection
SAMR is a frequent finding in patients with preformed DSA
SAMR reported to have an impact on long-term graft dysfunction and deterioration, instead of having an immediate impact
De Novo DSA in Post-Transplant Solid Organ Transplant Recipients
(dnDSA) post-transplantation has been as- sociated with higher graft failure rates.
the range of dnDSA:-
• 62% of liver transplant patients19
• 56% of lung transplant patients16
• 33% of heart transplant patients17
• 27% of multivisceral transplant patients18
• 24% of kidney-pancreas transplant patients
DSA is Predictive of Lower Graft Survival
the risk of developing chronic rejection leading to AMR increases with the presence of anti-HLA-Class II antibodies.
the presence of HLA antibodies predicts kidney graft loss.
In addition to rejection and graft loss, a significant association between the presence of anti-HLA antibody and patient survival has been demonstrated.
DSA Monitoring:
The C1q assay preferentially detects antibodies that have the capacity to fix and activate complement.
C1q (+) DSA were nearly 6 times more likely to lose their grafts than those with C1q (-) DSA.
C1q (+) DSA after transplant had AMR at the next biopsy, demonstrating that complement binding DSA is predictive of AMR.
The presence of C1q (+) DSA was associated with a significantly greater incidence of acute allograft rejection, and patients with C1q (+) DSA were significantly more likely to have C4d deposition found on biopsy.
Post-transplantation Monitoring:
Serial monitoring of the alloantibodies follow- ing transplantation may facilitate early diagnosis of chronic rejection.
DSA monitoring may be useful in the adjustment of immunosuppressive therapy post-transplant.
DSA monitoring may be useful in the adjustment of immunosuppressive therapy post-transplant. The close surveillance of humoral immunity is mandatory for the precise adjustment of anti-humoral therapy and optimal outcomes.
Why Monitor DSA Post-Transplant?
• Ten-year renal allograft survival in early antibody developers (<1 year) was 27% vs. 80% in the late antibody developers.
• More than 40% of kidney transplant recipients with AMR developed transplant glomerulopathy.
• Solid organ transplant recipients diagnosed with transplant glomerulopathy experienced 5-year graft
survival rates less than 50% from the time of diagnosis.
• 15-year graft survival in early antibody developers (<1 year) was 52% vs. 40% in late developers.
• De novo DSA production in heart transplant recipients was strongly associated with decreased patient
survival (HR = 3.198) and worse for those with persistent DSA (HR = 4.351).
• Many post-transplant solid organ transplant recipients developed de novo DSA secondary to
non-adherence to immunosuppressive therapy, particularly in the pediatric population.
• Insufficient immunosuppression may contribute to the development of de novo DSA and AMR
secondary to misclassifications based on C4d negativity
Why Monitor With Single-Antigen Beads?
Luminex®-based single-antigen beads (SAB) allow for a precise, highly sensitive determination of a patient’s antibody profile. This makes discrimination between donor-specific and non-donor-specific antibodies pos- sible.
The use of Luminex® SABs as part of a comprehensive monitoring program provides a number of advantages, including:
• The presence of low-level DSA can put patients at
risk for rejection
• Changes in DSA or the appearance of new DSA
specificities may reveal an early rejection process
Sensitivity of Antibody Detection Methods
Optimizing DSA Monitoring Strategies
Choosing a monitoring frequency based on a patient’s individual risk of developing AMR post-transplant will be the most efficient and clinically relevant strategy.
In your own words, summarise the role of anti-HLA Antibodies in Transplantation
Anti HLA antibodies are either pre-formed which is present in the patient serum as a result of sensitizing event pretransplant (blood transfusion, pregnancy, previous transplant) or formed de novo post transplantation. Whether detected pre or post transplantation, they are associated with increased risk of graft loss and/or rejection. DSA attack the endothelium resulting in ABMR.
Preformed DSA can cause instant hyperacute rejection and graft necrosis, also they can cause early acute ABMR. De novo DSA can cause late acute ABMR, chronic ABMR & transplant glomerulopathy. The clinical phenotypes of ABMR are determined by the complex characteristics of DSAs including HLA classes, specificity, strength, IgG subclasses, and complement binding capacity.
DSA may develop without causing an immediate impairment of graft function, this type of rejection is called subclinical rejection and is associated with long term graft dysfunction. DSA is also a predictive of lower patient survival.
How would you monitor DSA post-transplantation?
The patient immune risk should be stratified before deciding on DSA monitoring regimen, the risk classified as:
Testing for DSA should be done in all kidney transplant recipients at least one time in the first 3-12 months post transplant.
For subsequent determination:
The monitoring periodicity should be adjusted according to the patient’s clinical situation.
Proceeding to DSA level monitoring regardless of the risk level is required in the following conditions:
Reference:
Crespo M.,Zárraga S., Alonso A., Beneyto I., et al. Monitoring of Donor-specific Anti-HLA Antibodies and Management of Immunosuppression in Kidney Transplant Recipients: An Evidence-based Expert Paper.
Transplantation. August 2020,Volume 104,Number 8S2.
nicely written
Thank you
1. In your own words, summarise the role of anti-HLA Antibodies in Transplantation.
Anti-HLA antibodies are those antibodies which are formed in a transplant recipient due to exposure to a sensitization event like prior transplant, blood transfusion or pregnancy. Antibodies can develop post-transplant (de-novo) due to HLA mismatch, under-immunosuppression, as well as acute insults like acute T cell mediated rejections, infections etc.
These antibodies act at the vascular endothelium of the renal graft, leading to antibody mediated rejection, which would cause chronic damage in the graft ultimately reducing graft function and survival. It has been shown that upto 96% of patients with graft rejection develop DSAs. Early and acute AMR is usually seen with pre-formed DSAs while late chronic AMR is seen with de-novo DSAs. AMR in graft with de-novo DSA have poorer prognosis than in patients with pre-formed DSAs. DSAs are also associated with subclinical AMR, which is usually seen in patients having under-immunosuppression due to non-adherence.
If de-novo antibody develop after first year of transplant, the 15 year graft survival falls to 40% as compared to 52% in patients who develop de-novo DSA within 1 year of transplant. de-novo DSA, especially against class II HLA are associated with poor graft and patient prognosis. DSA is associated with severe forms of rejections.
DSA monitoring post-transplant is important to diagnose subclinical AMR as well as clinical AMR and to tailor immunosuppression according to patient-donor characteristics (for example decision regarding augmenting or reducing immunosuppression in presence of side-effects).
DSA monitoring involves single antigen bead assay as well as C1 q assay which is more specific for complement fixing and activating antibodies. Early detection of DSA and treatment to reduce them leads to better graft survival.
2. How would you monitor DSA post-transplantation?
Post transplant DSA monitoring is an important step in transplant management.
Guidelines (1) recommend:
In low risk group (first transplant, no desensitization, no DSA pre transplant): Check DSA at least once in first 3 to 12 months post transplant.
In Intermediate risk group (DSA negative, but prior history of DSA presence): Check DSA in first month post transplant
If DSA is negative, no further testing is required in these 2 groups unless there is change in immunosuppression, graft dysfunction, non-adherence or if the patient is transferred to remote unit.
If DSA is positive, kidney biopsy is done and if it shows AMR, it should be treated.
In high risk group (DSA positive) and very high risk group (desensitized cross match positive), DSA testing with kidney biopsy should be done during first 3 months. If biopsy shows AMR, treatment should be initiated. If biopsy is negative, but DSA rising, then it should be treated as AMR. If no AMR in biopsy, monitor DSA.
After one year post transplant, routine DSA monitoring is not recommended except if there is change in immunosuppression, graft dysfunction, non-adherence or if the patient is transferred to remote unit.
But a recent paper (Crespo et al, Transplantation 2020) recommends DSA monitoring in low risk group at least once in 12 to 24 months and in other groups annually.
References:
1) Tait BD, Susal C, Gebel HM, et al. Consensus Guidelines on the Testing and Clinical Management Issues Associated With HLA and Non-HLA Antibodies in Transplantation. Transplantation 2013;95:19-47.
2) Crespo M, Zarraga S, Alonso A, et al. Monitoring of Donor-specific Anti-HLA Antibodies and Management of Immunosuppression in Kidney Transplant Recipients: An Evidence-based Expert Paper. Transplantation 2020;104:S1-S12.
Excellent reply. Can you provide evidence for your statement” It has been shown that upto 96% of patients with graft rejection develop DSAs”
This statement is based on work by Lee et al, published in 2009.
Lee PC, Zhu L, Terasaki PI, et al. HLA-specific antibodies developed in the first year posttransplant are predictive of chronic rejection and renal graft loss. Transplantation 2009;88:568–574.
Summary of the role of anti-HLA Antibodies in Transplantation.
Presence of DSA either preformed or de novo Is well known risk initiate an immune response against graft endothelial cells and results in AMR .
solid-phase assays allowing for the accurate identification of DSA both pre- and post- transplant.
There is a strong evidence that anti-HLA Ab results in renal allograft failure.The early detection and removal of DSA associated with AMR, both pre- and post-transplant, may prevent allograft loss.
Types of AMR;
Antibody mediated rejection can present as an early acute process due to preformed DSA or de novoDSA, or late and may be chronic rejection
usually due to de novo antibody production.
preformed DSA is a significante risk of acute AMR which will lead to lower graft survival.
Chronic rejection is a major cause of graft loss occurs due to repeated cycles of AMR and repair result in distinct changes in the microvasculature of the allograft.
Patients with preformed DSA and those who develop de novo DSA are at an increased risk of having chronic rejection.
Sub-clinical antibody mediated rejection occurs when DSA either preformed or de novo without immediate affection of graft function but causes long term graft dysfunction.
non-adherence to IS therapy is a common cause of SAMR.
Renal biopsy after one year showed microcirculatory inflammation denoting presence of de novo DSA and C4d stain msy be negative for SAMR.
ROLE OF DSA IN SOLID ORGAN TRANSPLANTATION
De novo DSA is associated with high risk of graft failure of different solid oragans with highest level in liver transplants 62% and lowest in renal graft 24%.
DSA against HLA antigens specially class II is associated with higher incidence of AMR ,SAMR and chronic rejection with poor outcome on both patients and graft survival.
MFI value also affect the graft survival where MFI > 3000 had poor graf survival and 6000 MFI had the highest risk of graft loss by AMR.
Presence of DSA may predict rejections and graft failure in different solid oragans transplant as in liver and pancreas transplant , detection of DSA in serum is more valuable than doing biopsy in diagnosing AMR and steroid resistant liver rejection.
C1q assay detects IgG antibodies that can fix and activat the classical complement pathway with exclusion of non-complement fixing antibodies which may be clinically irrelevant to organ rejection.
C1q+ DSA is associated with significant higher incidence( up to 6 fold ) of acute rejection and more C4d deposition.
Post-transplant DSA monitoring:
It is important to allow early diagnosis of chronic rejection, antibodies may take months to years to produce the chronic vascular changes leading to graft failure, early treatment remove DSA will improve the outcome.
Also identify non adherent patients at risk of rejection.
Proper adjustment of anti-humoral immunosuppressive therapy post-transplant.
HOW TO DETECT DSA
Luminex based single antigen beads determine the patient’s antibody profile, and allow differentiation between donor and non-donor specific antibodies, determine the presence of low level DSA which can increase risk of rejection and detect changes in DSA that may reveal an early rejection process.
Timing for assays must be tailored according to each patient risk
Serial monitoring of DSA is more valuable than single point testing, particularly in the post-transplant setting, and is crucial in optimizing patient outcomes
Kimball et al. performed quarterly monitoring of patients for 3 years post-transplant and reported that 65% of patients eliminated antibody within the first year of transplant due to early detection and subsequent treatment. In those patients that exhibited pre-transplant DSA against Class I and II HLA, antibody levels declined by 90% at 6 months and were undetectable at 1 year with effective treatment.
your answer needs to be organised.
DSA against HLA class I and class II mismatches has been a significant . Whether detected pre- or post-transplant, the presence of antibodies directed against antigens expressed on donor organs, when not treated clinically, lead to increases risk of graft loss and/or rejection.
Sub-clinical antibody mediated rejection: DSA may also lead AMR without affecting the kidney function leading to decrease graft survival .
De Novo DSA in Post-Transplant: De novo donor-specific HLA antibodies (dnDSA) post-transplantation has been associated with higher graft failure . The range of dnDSA is 24% to 62% with the highest presence in post liver transplant recipients .In liver transplantation The presence of de novo DSA within the first year of liver transplants was more common in patients that presented with a chronic rejection; 92% had detectable DSA before chronic-rejection-induced graft failure occurred . DSA can be used to detect rejection early in pancreas, multi-visceral , small bowel transplants and in lung transplant where Anti-HLA antibodies are associated with a higher prevalence of Bronchiolitis Obliterans Syndrome which end with short graft survival
Antibodies in heart transplant may activate complement and accelerate Cardiac allograft vasculopathy which is the primary cause of death and re-transplant in long-term .
How would you monitor DSA post-transplantation? DSA should be monitor at 1,3,6 and 12 months after transplantation , then once per year. Patients a significant increase in DSA titer, allograft biopsy may be indicated . Protocol biopsies to detect subclinical rejection .
Expand your answer, you have missed various important information that shall compliment the report.
In your own words, summarise the role of anti-HLA Antibodies in Transplantation.
Antibodies were found in 25% at any given time in a cohort of transplant recipient. DSA are present in 96% of rejected grafts. These can develop pre-transplant (preformed) or they can develop de novo after transplant at any point of time. de novo DSA are due to noncompliance or insufficient immunosuppressant drugs
Detection of antibodies whether preformed or de novo and determining whether they are DSA is valuable for choosing induction, desensitization, immunosuppressants or changing dosed.
Both types can result in early graft dysfunction , acute ,subclinical or chronic AMR, which can end with graft loss and reduced 5 year patient survival (the later with DSA)
DSA are associated with subclinical rejection and transplant glomeulopathy and hence with reduced graft survival .
DSA presence, persistent, type ( esp class II DSA ) and high titer can predict graft loss and risk chronic rejection.
De novo DSA can end with graft failure (range from 62% in liver transplant up to 24% in kidney-pancreas transplant.
in liver transplant and in pancreas transplant , detection of DSA in serum is more valuable than doing biopsy in diagnosing AMR and steroid resistant liver rejection
DSA can be used to detect rejection early in pancreas, multi-visceral , small bowel transplants and in lung transplant where Anti-HLA antibodies are associated with a higher prevalence of Bronchiolitis Obliterans Syndrome which end with short graft survival
Antibodies in heart transplant may activate complement and accelerate Cardiac allograft vasculopathy which is the primary cause of death and re-transplant in long-term
How would you monitor DSA post-transplantation?
Through Luminex based single antigen beads (SAB) to detect low titer and determine the type of antibodies.
The frequency of testing is better to be patient specific and to be done periodically. The utmost benefit will be within the first year post transplantion especially for sensitized patients.
C1q assay detect complement fixing DSA which can predict AMR in heart and renal transplant as proved by studies
Expand your answer especially section 2 – How would you monitor DSA post transplantation? It needs more facts, figures and effort.
Early detection of DSA provide a tool to pick AMR at an early stage which would provide a chance for rescuing the graft
According to TTS the frequency of monitoring should be based according to the degree of risk low risk individuals are screened once from 3-12 months post transplant . Intermediate risk need screen in the first month . At any point,once DSA are detected ,a biopsy need to be taken to look for AMR. High risk and very high risk need a biopsy in the first month.
Role of anti-HLA antibodies in transplant:
Anti-HLA antibodies are preformed circulating antibodies in recipients due to sensitization (blood transfusion, pregnancy or previous transplant), detected pre or post-transplant, directed against antigens expressed on donor organs, attack the endothelium causing AMR.
Progression of DSA development, if not clinically treated, leads to chronic changes which decrease graft function and survival.
Sub-clinical antibody mediated rejection:
Type of rejection where DSA develop without immediate affection of graft function but cause long term graft dysfunction.
Common in patients with preformed DSA, and who are non-adherent to immunosuppressive therapy.
Allograft biopsy one year post transplant mostly show microcirculatory inflammation denoting presence of de novo DSA
De novo DSA post-transplant:
The negative outcome of de novo DSA may appear several years after production of the antibodies.
Studies showed that de novo DSA against class II HLA mismatches have worse outcome, associated with higher risk of chronic rejection and AMR
DSA is predictive of lower graft survival:
HLA antibodies are predictive of graft loss.
Studies showed that presence of anti-HLA antibodies is associated with poor patient survival.
Effect of C1q DSA on allograft survival:
Novel C1q assay detects IgG antibodies capable of fixing and activating the classical complement pathway with exclusion of non-complement fixing antibodies which may be clinically irrelevant to organ rejection.
It is used with other methods to define patient’s immunological profile.
C1q+ DSA is associated with significant higher incidence of acute rejection and more C4d deposition on biopsy.
Post-transplant DSA monitoring:
• Serial monitoring of DSA post-transplant allow early diagnosis of chronic rejection, this is important as antibodies may take months to years to produce the chronic vascular changes leading to graft failure, early initiation of anti-humoral therapy can remove DSA and improve the outcome.
• Early identify patients at risk of rejection due to insufficient immunosuppression due to non-adherence
• Allow adjustment of anti-humoral immunosuppressive therapy post-transplant.
Luminex based single antigen beads determine the patient’s antibody profile, and allow differentiation between donor and non-donor specific antibodies, determine the presence of low level DSA which can increase risk of rejection and detect changes in DSA that may reveal an early rejection process.
thanks
1. In your own words, summarise the role of anti-HLA Antibodies in Transplantation.
The presence of anti-HLA antibodies whether preexisting or newly formed affects graft survival.
There are some criteria that are associated with poor graft survival:
1- DSA titer:
In the study by Lefaucheur et al (2010), DSA titer> 6000 MFI had the highest risk (100 fold) of graft loss by AMR. Also, graft survival was lower when MFI > 3000 in the same study.
2- DSA time of origin:
De novo DSA may confer a poorer graft outcome when compared with preexisting DSA. Yjis was illustrated by several studies. One of them was the study by Wiebe et al (2012), the median 10-year graft survival for those with de novo DSA was lower than the No de novo DSA group (57% vs. 96%, p<0.0001).
3- DSA class:
In a study by Lefaucheur et al (2016), IgG4 was associated with a delayed allograft loss, while IgG3 conferred a faster graft loss.
4- DSA responsiveness:
Many trials were in concordance that DSA response to immunosuppressive medication was associated with more favorable allograft survival.
5- C1q binding ability:
Although some studies revealed that DSA antibody ability to bind with complement was associated with poorer outcomes (Loupy et al, 2013), some authors contradict this finding proposing that complement binding is related only to antibodies strengths (Yell et al, 2015).
1. How would you monitor DSA post-transplantation?
DSA should be routinely performed at 1,3,6 and 12 months after Tx, then once per year. For those patients who show a significant increase in DSA titer, allograft biopsy may be warranted. (Tait BD et al, 2013)
Thank you
Well done
Roles of anti-HLA antibodies in kidney transplantation
The presence of antibodies directed against donor antigens ,whether pre or post kidney transplant results in an immune attack on the endothelium of the allograft, resulting in subsequent AMR . Sub clinical-AMR is also a frequent finding in patients with preformed DSA . There is strong evidence that anti-HLA antibodies contribute to the development of graft nephropathy, the leading cause of renal allograft failure . Survival was significantly worse in recipients who had persistent DSA than in those who had cleared the DSA. Death-censored allograft survival stratified by percent reduction in immune dominant DSA at 14 days post-biopsy Renal allograft survival stratified on ability to yield antibody reduction . The development of de novo donor-specific HLA antibodies (dnDSA) post-transplantation has been associated with higher graft failure rates. May cause sub-clinical AMR that is associated with long term graft dysfunction .The range of dnDSA is 24% to 62% with the highest presence in post liver transplant recipients. Several prospective and retrospective studies have demonstrated that de novo DSA development in renal transplant patients, predominately directed at Class II donor HLA mismatches, is associated with poor outcomes, and is often detectable well before graft failure.
DSA monitoring ;
The routine monitoring of DSA may provide early identification of those patients at risk for rejection due to insufficient immune suppression as a result of poor compliance with immunosuppressive therapy. DSA monitoring may be useful in the adjustment of immunosuppressive therapy post-transplant . Studies have shown that when DSA is identified early through routine monitoring, the initiation of anti-humoral therapy may begin sooner, allowing for DSA to clear and improving overall survival rates. Research has suggested that the evaluation of the C1q assay provides a further layer of immunologic antibody information that may prove to be an adjunct in optimizing post-transplant care. In a study reported by Yabu et al., kidney transplant recipients with C1q (+) DSA were nearly 6 times more likely to lose their grafts than those with C1q (-) DSA.
Optimize DSA monitoring strategies
Choosing a monitoring frequency based on a patient’s individual risk of developing AMR post-transplant will be the most efficient and clinically relevant strategy. Serial monitoring of DSA is more valuable than single point testing, particularly in the post-transplant setting, and is crucial in optimizing patient outcomes. In those patients that exhibited pre-transplant DSA against Class I and II HLA, antibody levels declined by 90% at 6 months and were undetectable at 1 year with effective treatment.
Thanks
The Role of anti-HLA Antibodies in Transplantation
The Spectrum of Antibody Mediated Rejection
Early or late antibody mediated rejection is associated with deleterious renal outcomes. The presence of preformed or de Novo anti-HLA DSAs carry high risk of humoral rejection.
Preformed antibodies are implicated in the development of early acute rejection while de novo DSA can develop in the early and late post-transplant period, resulting in disastrous inflammatory response and graft failure.
Patients with preformed DSA and those who develop de novo DSA are at an increased risk not only for acute rejection but also chronic rejection based on the histopathological Banff criteria.
Sub-Clinical Antibody Mediated Rejection
The development of biopsy proven signs of rejection in the presence of DSA defines subclinical AMR. Subacute rejection has been reported to have an impact on long-term graft dysfunction.
Subacute rejection is a common finding in patients with preformed DSA, even with negative C4d. The detection of De novo antibody could be histologically reflected by subclinical AMR, which is associated with long- term negative outcomes typically occurring several years after de novo antibody production.
The majority of de novo DSA are directed against Class II donor HLA in particular with HLA class II mismatches.
DSA is Predictive of Lower Patient Survival
In terms of survival outcomes, survival was significantly decreased at 5-years post-transplant in DSA positive patients compared to DSA negative patients.
The Future of DSA Monitoring: Effect of C1q DSA on Allograft Survival
C1q assay is used to detect IgG antibodies capable of fixing complement and developing cell lysis.
In one study, kidney transplant recipients with C1q (+) DSA were nearly 6 times more likely to lose their grafts than those with C1q (-) DSA. The presence of C1q (+) DSA was associated with a significantly greater incidence of acute allograft rejection, and patients with C1q (+) DSA were significantly more likely to have C4d deposition found on biopsy. The C1q assay preferentially detects antibodies that have the capacity to fix and activate complement.
Post-transplantation Monitoring
Serial monitoring of DSA in sensitized, mismatched recipients or in centers with protocol biopsies and finally in patients with deterioration of kidney function, is essential for early detection of alloantibodies following transplantation. Early diagnosis of acute or chronic rejection with appropriate management is associated with better outcomes. In patients at risk for rejection, DSA monitoring may be helpful in the adjustment of immunosuppressive therapy post-transplant.
Why Monitor DSA Post-Transplant?
-Ten-year renal allograft survival is poor in early antibody developers .
-High risk of transplant glomerulopathy in recipients with AMR.
-Survival rates in recipients diagnosed with transplant glomerulopathy is less than 50% from the time of diagnosis.
-Graft survival in early antibody developers is better than late developers.
-De novo DSA formation is strongly linked with non-adherence to immunosuppressive therapy.
Why Monitor With Single-Antigen Beads?
Luminex-based single-antigen beads remains the better diagnostic test to detect with high specificity anti-HLA DSA allowing for high sensitive determination of a patient’s antibody profile.
How often should we monitor DSA?
In spite significant improvement in post-transplant care, long term graft function is less than optimal.
Antibody mediated rejection (AMR) due to late stage graft failure is a main cause of poor graft survival .
The presence of antibodies directed against donor antigens results in an immune response on the transplanted organ, and increases risk of graft rejection if not treated.
Anti-HLA antibodies contribute to the development of renal allograft failure. The early identification and removal of DSA occurring with AMR, both pre- and post-transplant, can prevent allograft loss.
Highly sensitive and specific solid-phase assays enable detection of DSA both pre- and post- transplantation
Antibody mediated rejection can occur early by preformed DSA while late and chronic rejection can occur by denovo DSA.
subclinical antibody mediated rejection SAMR caused by DSA affects long-term graft function negatively.
For SAMR some cases are negative for C4d stain caused by non-adherence to immunosuppressive therapy leading to microcirculation inflammation on renal biopsies 1 year post transplantation.
The detection of denovo DSA was associated with high rate of graft failure, the biggest percentage was identified in liver transplant recipients.
Studies have concluded that HLA antibodies can predict renal graft loss.
In liver transplantation the differentiation between AMR and cholethiasis is difficult clinically and pathologicaly.
The diagnosis of AMR in liver transplant recipients can be by the presence of DSA in the recipient serum.
Bile duct injury in Cd4 livetransplant recipents is associated with DSA
In pancreatic transplantation the presence of pretransplant and posttransplant DSA indicates poor graft outcome
DSA monitoring in pancreas, multi-visceral and small bowel transplants is an important diagnostic tool in early diagnosis and treatment of acute rejection.
Anti-HLA antibodies are accompanied by the occurrence of Bronchiolitis Obliterans Syndrome , it can predicts its occurrence nearly 1 year before its occurrence.
Circulating antibodies can lead to cardiac allograft vasculopathy leading to graft loss in cardiac transplantation.
Monitoring of the DSA post transplantation may enhance early diagnosis of chronic rejection specialy due to inadequate immunosuppresion.
How to monitor DSA
-By using Luminex SAB to detect low levels of DSA and newly developed DSA which affects directly graft survival and management.
-C1q DSA complent fixing antibody specifically need to be identified as not all non complement fixing DSA are associated with graft loss ,suggesting that C1qDSA monitoring is crucial in predicting AMR.
A study demenostrtated that patients with C1q (+) DSA were more prone to have C4d deposition on biopsy.
Thanks
Donor-specific antibodies (DSAs) can be classified according to the time of detection into a preformed DSA detected in the patient serum before transplantation and de novo DSA, which will be detected post-transplantation as a result of sensitization.
Risk factors for developing preformed DSA
Risk factors for developing denovo DSA
The Role of anti-HLA Antibodies in Transplantation
DSA either preformed or formed after transplantation attacks the endothelium of the graft leading to :
· Acute ABMR
· Chronic ABMR
· Subclinical rejection
· All cause subsequent reduction of graft and patient survival
Although, preformed DSA is associated marked increase in the Incidence of occurrence of early ABMR and reduced graft survival, De-novo DSA associated AMR has poorer graft survival as compared to pre-existing DSA associated AM
Monitoring of DSA
Why
1- Diagnostic : since subclinical and clinical ABMR can occur either due to Planned subtherapeutic immunosuppression (due to malignancy, infection) or conversion to CNI free or CS free protocols or noncompliance on immunosuppressive medication
2- Therapeutic: immunosuppressive medications can be tailored according to DSA level
3- Prognostic : presence of DSA in the early post-transplant period is associated reduced graft survival when compared to DSA developed later on after 1 year (10 years graft survival 27% vs 80%, respectively), > 40 % of patients with ABMR develop transplant glomerulopathy which reduce significantly graft survival (5 years graft survival in patient with TG is < 50%)
How
When
DSA should be monitored once in early post-transplant period (first 3 month) in all patients
After first 3 month no further testing is required except in the following situations
⦁ Patients who has received desensitization to render cross match negative (only for first 1 year post transplant)
⦁ Modification of immunosuppression
⦁ Suspicion of non-adherence
⦁ Graft dysfunction
⦁ Transfer of the patient to another center
Some recommend assessment of DSA annually,
Some recommend measurement of DSA / 3months for first 3 years
What to do after detection of DSA
All patients with detectable DSA should undergo renal biopsy
Treatment is indicated in the following situations
1- Presence of DSA together with histologic features of ABMR
2- Rapid increase of DSA with normal or near normal biopsy in in patients who received desensitization to render cross match negative
Thank you for putting your summary in the form of questions (excellent)
In your indications you stated graft dysfunction you know quite well that by the time this happens the immune damage has long been taking place.
Well done
Very structured answer.
graft survival from either deceased or living donor is still not optimal in spite of good patient and graft care with advancement of immunosuppressive medications, chronic AMR is the major cause for graft loss.
Detection of DSA either early or post transplant is very important to guard against development of AMR which results from endothelial injury caused by attacking DSA, so its removal is the key to prevent AMR and improve graft survival.
Solid phase assay can be used for detection of DSA by SAB (single antigen bead).
Preformed DSA can induce immediate AMR or may not lead to graft dysfunction immediately and may induce its effect late and predispose to chronic AMR due to previous subclinical AMR.
Subclinical AMR (either c4d positive or negative) may be related to preformed DSA or de novo DSA caused by non-adherence or dose reduction of ISD.
De novo DSA developed post-transplant affects graft survival especially liver graft, and cardiac graft. In renal graft, it is developed and directed to class II HLA antigen, and is associated with negative impact on graft and patient survival.
In liver transplant, diagnosis of AMR is based on the presence of DSA in the patient serum, and is associated with negative outcome.
In the pancreas transplantation, diagnosis of AMR is complexed and not easy, so depending on the presence of DSA is crucial in the diagnosis of AMR which also associated with negative outcome.
Not all DSA are injurious to the graft with the same degree, so, determine the type is important.
Complement fixing is determined by C1q assay and c4d stain.
C1q DSA (c4d positive stain) is associated with acute AMR and negative impact on graft survival than negative C1q DSA.
Yearly monitoring of DSA is beneficial to detect any abnormality or early rejection attack hence augment ISD or adjust doses, this monitoring can be done by luminex SAB due to high sensitivity of it.
Very good for highlighting the time lapse between there detection and immune injury
Also the type of DSA. Class1or class2
The role of anti-HLA Antibodies in Transplantation:
Monitoring of DSA post-transplantation:
The routine monitoring of DSA may provide early identification of those patients at risk for rejection due to insufficient immunosuppression as a result of poor compliance with immunosuppressive therapy.
Better work this time as you are using your own words a bit more.
Summering should be: Read, understand, and summarize in your own words.
1- In your own words, summarise the role of anti-HLA Antibodies in Transplantation.
2- How would you monitor DSA post-transplantation?
Very sufficient informative summary.
How would you monitor DSA post-transplantation?
Post transplantation (months 0 – 12)
a. Very high risk patients (desensitized):
Monitor DSA and conduct protocol biopsies in the first 3 months after transplantation.
1. If there is evidence of clinical or subclinical AMR, the patient should be treated.
2. If there is a rapidly increasing level of DSA accompanied by a biopsy showing no rejection, initiation of therapy to reduce the DSA levels should be considered.
b. High-risk patients (DSA positive/XM negative):
Monitor DSA and conduct a protocol biopsy in the first 3 months after transplantation.
1. If biopsy is positive for AMR, the objective is to treat.
2. If there is a rapidly increasing level of DSA accompanied by a biopsy showing no rejection, initiation of therapy to reduce the DSA levels should be considered.
3. DSA persists in the absence of biopsy proven rejection, immunosuppression should not be reduced, and additional monitoring should be considered.
4. If the DSA and biopsy are negative, follow as if low risk unless there is an inflammatory event,
in which case additional monitoring for DSA is recommended.
c. Intermediate-risk patients: Includes history of sensitization to donor antigen(s) by CDC and SPI but currently negative and history of sensitization with at least one positive test for HLA antibodies. Monitor for DSA within the first month.
1. If a DSA present, then perform a biopsy.
2. If biopsy is positive for rejection, the objective is to treat.
3. In the absence of biopsy-proven rejection, additional DSA monitoring should be considered within the first year.
4. Patients with a DSA in the absence of biopsy-proven rejection should not be considered for reduction in immunosuppression.
5. In the absence of a DSA follow-up as if low risk .
d. Low-risk patients (nonsensitized, first transplantation)
1. Screen for DSA under the following circumstances:
a) at least once in 3 to 12 months after transplantation.
b) whenever significant change in maintenance immunosuppression is considered (e.g., minimization/withdrawal/conversion).
c) suspected nonadherence.
d) graft dysfunction.
e) before transfer of care to a remote center outside the transplant center.
2. If DSA present, then perform a biopsy.
3. If the biopsy is positive for rejection the objective is to treat.
4. In the absence of biopsy-proven rejection ,additional DSA, monitoring should be considered within the first year.
5. Patients with a DSA in the absence of biopsy-proven rejection should not be considered for reduction in immunosuppression.
6. If no DSA present, then no additional testing in the first year is recommended in the absence of circumstances listed under point 1 above.
Post transplantation (month 12 onward) applies to all risk categories
a. Store at least one serum sample per year (i.e., on the transplantation anniversary).
b. Evaluate DSA in a current serum if any of the following conditions occur:
1. Significant change in maintenance immunosuppression is considered (e.g., minimization/withdrawal/ conversion).
2. Suspected nonadherence.
3. Graft dysfunction.
4. Before transfer of care to a remote center outside the transplant center.
c. If de novo DSA present or if there is an increase in previous DSA levels, perform a biopsy.
1. If biopsy is positive for AMR, the objective is to treat.
2. If biopsy is negative (no sign of rejection) monitor the DSA and monitor for a change in graft function.
3. Patients with a DSA even without biopsy proven rejection should not be considered for reduction in immunosuppression.
Consensus Guidelines on the Testing and Clinical Management Issues Associated With HLA and Non-HLA Antibodies in Transplantation
Brian D. Tait et al
In your own words, summarise the role of anti-HLA Antibodies in Transplantation.
HLA antibody play a central role in graft survival.
There is a correlation between HLA antibodies and graft rejection.
Pre transplant immunosuppression needs to be tailored according to the DSA MFI levels.
Persistence of DSA at 1 year is associated with decreased gfr and chronic abmr.